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Identification of the Optimum Latent Fingerprint Recovery Method from Pig Skin at

Varying Temperatures

by Jasmine Siah

Thesis submitted in fulfillment of the requirements for the degree of Master of Forensic

Science (Professional Practice & Research)

in

Faculty of Medical, Molecular and Forensic Sciences

Murdoch University

Supervisors:

Associate Professor James Speers (Murdoch)

Elliot Cottrill (WA Police)

Semester 2, 2020

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Declaration

I declare that this thesis does not contain any material submitted previously for the award of

any other degree or diploma at any university or other tertiary institution. Furthermore, to

the best of my knowledge, it does not contain any material previously published or written

by another individual, except where due reference has been made in the text. Finally, I declare

that all reported experimentations performed in this research were carried out by myself,

except that any contribution by others, with whom I have worked is explicitly acknowledged.

Signed:

Jasmine Siah

03/08/2021

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Acknowledgements

I would like to acknowledge and express my gratitude to my supervisors, Associate Professor

James Speers and Elliot Cottrill for their constant guidance and support throughout the

completion of my project.

To Wong Zsa Zsa and Lance Boston, thank you for assisting me in the project by providing me

with pig skin during the preliminary studies and piglets during the project. To Bob Du and Sun

Litao, thank you for assisting in the completion of my project by giving me permission to use

the temperature and humidity cabinets.

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Table of Contents

Title Page……………………………………………………………………………………………………………………………. 1

Declaration…………………………………………………………………………………………………………………………. 2

Acknowledgements……………………………………………………………………………………………………………. 3

Part One

Literature Review…………………………………………………………………………………………………………. 6 - 49

Part Two

Manuscript……………………………………………………………………………………………………………………

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This page has been intentionally left blank

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Part One

Literature Review

Identification of the Optimum Latent Fingerprint Recovery Method from Pig Skin at

Varying Temperatures

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Abstract:

Successful development of latent fingerprints in criminal investigations can be extremely

beneficial in solving cases. Many studies have been undertaken to identify the most effective

method for the recovery of latent fingerprints from various surfaces and it was determined

that human skin is one of the most difficult surfaces for fingerprints development. However,

it is desirable for investigators to obtain latent fingerprints from human skin as physical

contact between perpetrators and victims are very common. In light of that, researchers have

tested different methods such as alternative light sources, dactyloscopic powders, chemicals,

direct transfer and more on skin and have been successful but not without challenges. Factors

such as normal body functions, skin conditions, environmental conditions, post-deposition

conditions and environmental contaminants can all affect the durability of latent fingerprints

and the recovery rate. Hence, results may vary in terms of efficacy in different cases,

conditions and countries where many of these factors are different. In cases where

fingerprints are smudged or distorted, sweat residue in treated latent fingerprints may be

used for DNA recovery which if treated properly can generate DNA profile of person of

interest. Nonetheless, some latent print enhancement techniques provide more hindrance to

the DNA recovery process than others. This paper presents a comparative analysis on the

different recovery techniques tested for the development of latent fingerprints on skin and

the overview of how the many challenges affect the durability of latent fingerprints and

success rate of recovery.

Keywords: latent fingerprints, human skin, powdering methods, chemical methods, DNA

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Table of Contents:

Abstract……………………………………………………………………………………………………………………..……… 7

List of Figures……………………………………………………………………………………………………………..……... 9

List of Table……………………………………………………………………………………………………………………….. 9

List of Abbreviations…………………………………………………………………………………………………..…….. 9

1.0 Introduction…………………………………………………………………………………………………………........ 10

2.0 Discussion…………………………………………………………………………………………………………………… 15

2.1 Physiology of Skin……………………………………………………………………………………………........ 15

2.1.1 General anatomy of skin……………………………………………………………………………………… 15

2.1.2 Secretion glands………………………………………………………………………………………………….. 16

2.1.3 Thermoregulation.………………………………………………………………………………………………. 18

2.1.4 Human skin as substrate……………………………………………………………………………………… 19

2.2 Latent Fingerprint Recovery Techniques…………………………………………………………………. 20

2.2.1 Powdering methods……………………………………………………………………………………………. 20

2.2.2 Fuming methods…………………………………………………………………………………………………. 22

i. Cyanoacrylate (CA) fuming…………………………………………………………………………………….. 22

ii. Ruthenium tetroxide (RTX) fuming……………………………………………………………………..…. 24

iii. Iodine fuming………………………………………………………………………………………………………… 25

2.2.3 Direct transfer…………………………………………………………………………………………………….. 25

2.3 Recovery of Touch DNA from Treated fingerprints…………………………………………………. 26

2.3.1 Techniques used in the recovery of touch DNA from latent fingerprints……………… 26

2.3.2 Effects Fingerprint Powders have on the Recovery of DNA…………………………………. 27

2.4 Factors affecting the Durability of Fingerprints…………………………………………………….… 28

2.4.1 Humidity……………………………………………………………………………………………………………... 29

2.4.2 Temperature……………………………………………………………………………………………………….. 30

2.4.3 Physical contact and contaminants……………………………………………………………….…….. 32

2.4.4 Skin conditions…………………………………………………………………………………………….……… 32

3.0 Experimental Design…………………………………………………………………………………………………… 34

4.0 Experimental Aim & Hypothesis…………………………………………………………………………………. 36

5.0 Conclusion….……………………………………..……………………………………………………………………….. 37

Reference List………….……………………………………………………………………………………………………….. 40

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List of Figures:

Figure 1: The three main classes of fingerprints

Figure 2: The three types of minutiae

Figure 3: Cross-section of Human Skin

List of Table:

Table 1: Bandey scale – grading system for the determination of the quality of ridge

details for developed fingerprints

List of Abbreviations:

POI Person of interest

ALS Alternative light source

DNA Deoxyribonucleic acid

CA Cyanoacrylate

RTX Ruthenium tetroxide

qPCR Quantitative polymerase chain reaction

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1.0 Introduction

Fingerprints are unique for every individual. There are no identical fingerprints that are same

in every single detail, not even for identical twins1. Fingerprints are made from a series of

ridges, valleys and whorls located on our fingertips2. These ridges are persistence and do not

alter over time unless they are mutilated or affected by accidents or skin diseases3,4. Because

of their uniqueness, fingerprints are one of the most valuable and compelling pieces of

evidence for a criminal investigation. Fingerprint identification is being used forensically by

experts for victim identification and placing persons of interest (POI) at crime scenes.

Fingerprint impressions are formed by natural substances secreted by the pores and glands

that are present on the friction ridges of the hands and toes and contaminants from the

environment5. The glands responsible for producing these secretions are the sebaceous,

apocrine and eccrine glands. Sebaceous glands secrete a mixture of lipids for skin and hair

protection6. Apocrine glands are mainly located in the anogenital region, armpits and areola

and the secretions are often accompanied by an odour. The eccrine glands are located mostly

on the palm and soles of the human body and it secretes sweat that are composed of mainly

water and mineral salts7. Besides these natural secretions, environmental contaminants such

as blood, grease, dust etc also contribute to the formation of latent fingerprints and these

deposits may have a longer lifespan than natural secretions5.

There are three types of fingerprint impressions namely patent, latent and plastic

impressions. Patent fingerprint impression is made when fingertips come in contact with a

surface resulting in the deposition of fingerprint residues on the surface and are easily visible

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to the naked eye8. They can be created by dirt or other liquids such as blood, ink and oil that

adhere to the fingerprint ridges. On the contrary, latent fingerprint impressions are 2-

dimensional prints that are invisible to the naked eye and therefore requires additional

visualisation and enhancement techniques. They are made of body secretions such as oil,

sweat, and contaminants that coat the ridges during deposition9. Last but not least, plastic

fingerprints are 3-dimensional impressions that can be easily detected by the human eye as

they are made in soft and malleable surfaces like soap, plasticine, wax, paint etc. resulting in

an indentation9.

Figure 1: The three main classes of fingerprints.

Fingerprints are categorised into 3 different classes – arch, loop and whorl as shown in Figure

1. These characteristics are used as the first level of detail in fingerprint identification which

refers to the overall ridge flow in the fingerprint10. An arch is shaped like a wave pattern that

begins from one end and terminates on the opposite end11. The loop pattern has additional

characteristics that are known as a core and delta. A loop has multiple ridges entering from

either side of the fingertips, re-curve at one point and ends in the same direction where the

ridges entered. Lastly the whorl pattern is circular in shape and is accompanied with type

lines and at least 2 deltas12.

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Figure 2: The three types of minutiae.

In addition to that, the second level of details refer to characteristics called minutiae.

Minutiae are the discontinuities displayed by the friction ridges and is categorised into

bifurcation, dot and ridge ending4,13. Bifurcation is ridges that split into two, dot refers to tiny

round ridges and lastly, ridge ending refers to the abrupt endings of ridges (Figure 2). Finally,

the third level of detail introduces features associated with the individual ridges. These

features include the width, size, shape, distribution of pores, scars and more that is unique

in every individual14.

A variety of techniques have been developed and are currently being used for the detection

and recovery of these ridge details for the purpose of making an identification. In some cases,

multiple treatment methods are required to clearly visualise the characteristics of the friction

ridges. The enhancement of the ridge details depends on the surface the fingerprints are

found on. These surfaces are generally grouped into porous and non-porous surfaces. Porous

surfaces tend to absorb substances deposited onto them while non-porous surfaces are

unable to do so. Hence, recovery of latent fingerprints is more difficult on porous surfaces as

compared to non-porous surfaces15.

Human skin is one of the most challenging surfaces for latent fingerprint recovery due to the

various physiological reasons such as regulation of body temperature, constant renewal and

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regeneration, elasticity of the skin, impact of environmental factors on the skin etc (16). Over

the past few decades, experts have been developing and using various techniques to recover

fingerprints from human skin but in majority of the cases, these techniques were only

successful under ideal laboratory conditions15. Researchers have attempted to recover latent

prints from living and dead human skin by using a variety of techniques e.g. alternative light

sources (ALS), direct transfer method, dusting, cyanoacrylate fuming and x-ray technique

prior to being lifted. Good quality prints with potential for identification were successfully

recovered in a number of studies, although the success rate is highly dependent on the

environmental conditions, skin types and other post-deposition conditions, some techniques

were observed to be more effective than others. Therefore, it is extremely crucial to learn of

the variables before deciding on the recovery techniques. More details on the effectiveness

of the various techniques will be discuss later in this review paper.

The quality and durability of latent fingerprints are affected by a number of factors such as

donor, weather, surrounding temperature and humidity, external contaminants, substrate

types etc. or a combination of these factors. These factors together may influence the

longevity of latent prints and induced reactions within the prints such as absorption,

adsorption, evaporation, oxidation, racemization and maybe others17.

Fingerprint impressions do not only provide patterns that are useful for identification, but

they also contain a good quantity of cellular materials that can be used to generate DNA

profiles18. As both fingerprints and DNA are evidences of high value, joining both pieces of

evidence can be crucial for forensic investigators19. Forensic workflow usually requires

evidence to be processed for fingerprints prior to any DNA recovery as the use of common

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DNA recovery methods often results in the damage of fingerprints present on exhibits20.

However, a new method was discovered where low-adhesive material is applied to the

surface for a few seconds to recover the traces of DNA-containing materials while preserving

the latent fingerprints19. In cases where fingerprints are enhanced but appeared smudged or

with poor quality, they will be used for DNA recovery after being recorded. Studies have

proven that the recovery and generation of DNA profiles from visually enhanced fingerprints

are feasible20-23. Certainly, some enhancement techniques yield more DNA than other

techniques18,21. Even though fingerprint powders are inexpensive and results are instant, it

also carries the risk of DNA cross contamination that occurs through the use of fingerprint

brushes14. The quality and quantity of DNA is also affected by the time between latent prints

development and DNA extraction18.

This paper aims to review the various techniques used for the development of latent

fingerprints from skin and their effects on human DNA recovery, and the effects of various

post-deposition conditions have on the durability and recovery of latent fingerprints from

skin.

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2.0 Discussion

2.1 Physiology of Skin

2.1.1 General Anatomy of Skin

Skin is the largest organ in the body and it protects the body against chemicals, pathogens,

ultraviolet (UV) radiation, regulates body temperature and allows us to feel and touch the

outside world24,25. Skin is mainly made up of the epidermis, dermis and hypodermis. The

thickness of each of these layers differ depending on the body region and is categorized

according to the thickness of the epidermal and dermal layers24.

Figure 3: Cross-section of Human Skin

The epidermis is the outermost layer and consists primarily of cells called dendritic cells and

keratinocytes. A number of other cell populations like melanocytes, Merkel cells and

Langerhans cells are also located in the epidermis, but keratinocytes comprises the majority26.

Keratinocytes produce keratin that form the water barrier by producing and secreting lipids;

melanocytes are responsible for pigmentation of skin; Merkel cells possess sensory functions

and are most abundant in the fingertips; Langerhans cells also called dendritic cells are part

of the immune system and are responsible for the uptake of antigens in skin and transporting

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them to the lymph nodes24,27. These cells can be found in four different layers including the

basal cell layer, squamous cell layer, granular cell layer and cornified cell layer26. As the

epidermis are exposed to direct and frequent damage due to the external world, the constant

repair and renewal of cells are extremely crucial. The cells in basal layer are what provide for

the constant renewal by going through proliferation cycles26. This constantly renewing layer

also prompts derivative structures like nails, sweat glands and pilosebaceous apparatuses26.

The second layer called dermis is thicker than the epidermis and provides flexibility and

strength 26,27. It is arguably the most important layer of the three. Besides the connective

tissues and blood capillaries, it also contains lymph vessels, sweat glands, sebaceous glands,

nerve endings and hair follicles that allow for the production of sweat and oil, regulation of

body temperature, hair growth, provide sensation, distribution of blood, protection of the

body and giving the skin structure28.

Hypodermis is the third layer of the skin that is directly below the dermis. It connects the skin

to the underlying fibrous tissues of the bones and muscles29. This layer contains hair follicles,

sweat glands, blood vessels, sensory neurons, connective tissues and mainly adipose

tissues24,30. Due to the large number of adipocytes in the adipose tissues, the hypodermis

provides insulation for the body to prevent heat loss, serves as an energy reserve, and protect

the underlying structures by providing a cushion27,29.

2.1.2 Secretion Glands

Fingerprints are formed by a complex mixture of natural secretions from the body and

environmental contaminants. The glands that play a role in the secretions of the skin are the

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sweat glands and sebaceous glands that are present in the integumentary system over most

part of the body31. Sweat glands originated from the epidermis but they lie in the dermal

layer32. The two distinct types of sweat glands are the apocrine and eccrine glands that have

different embryology, distribution and function33.

Eccrine glands are widely distributed across the entire body and are responsible for ion

excretion but primarily for thermoregulation34,35. They respond to both emotional and

thermal stimuli36. These glands are the most copious on the palms and soles which means

that the moisture on the fingertips mainly originates from sweat secreted from the eccrine

glands36. Eccrine sweat is made up of approximately 98.5% of water and therefore the

durability of fingerprint impressions made up eccrine secretions may be shorter31,34.

The apocrine glands developed adjacent to hair follicles and secretes through hair canals.

Hence, they are not functional until hormonal stimulation during puberty and can be found

only in skin that contains hair i.e. armpits, anal, areola, scalp and genital areas37,33. The

secretion consists of lipids, carbohydrate, protein, lipid, ammonium along with other organic

compounds and can cause odour37. Unlike eccrine glands, the apocrine glands respond only

to emotional stimuli rather than temperature37. Contamination by apocrine secretions is less

common in normal crimes but can be relevant when it comes to sexual crimes5.

Sebaceous glands are glands located in the dermal layer of the skin and are mostly open into

the hair follicles while there are also some that opens directly to the surface of the skin38,39.

These holocrine glands are not present on the palms of hands, the soles and dorsum of feet

and lower lip while the greatest concentrations are on the face, scalp, chest and upper

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neck38,40. They secrete an oily substance known as sebum that is responsible for lubricating

the skin for protection against friction and making it ‘waterproof’39,41. Latent fingerprints are

commonly contaminated by secretions of the sebaceous glands as it is easily transferred onto

the hands by natural everyday occurrences such as touching areas of the head when combing

the hair, postures when sitting and more31. Latent fingerprints that are contaminated with

the greasy secretions of sebaceous glands tend to remain durable for longer periods of time

as compared to sweaty fingerprints with high eccrine content5,42.

2.1.3 Thermoregulation

Thermoregulation is a self-regulated mechanism used by mammals to maintain stable body

temperature. It is a type of homeostasis as is completely independent of external

temperatures43. Regulation of body temperature is controlled by the hypothalamus through

the detection of internal body temperature and sending signals to the glands, skin, muscles

and organs43. When the body temperature is high, sweating and vasodilatation occur to cool

down the body; when the body temperature is low, hormonal thermogenesis, thermogenesis

and vasoconstriction occur to help increase the body temperature44.

Core temperature fluctuates throughout the day (circadian rhythm), month and lifetime45.

These fluctuations cause changes in the body’s thermoregulatory system and kick start

mechanisms to either increase or decrease body temperature. These mechanisms may affect

the quality of latent fingerprints that are deposited on the human skin. For instance, sweating

or the body’s perspiration can damage the fingerprints by ‘washing out’ the fingerprint

constituents46. Besides that, the normal body temperature maintains oily substances of

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fingerprints in liquid form that tends to disperse more easily46. Hence, these factors make

developing latent prints on live subjects a more difficult task compared to on skin of cadavers.

When an individual dies, algor mortis sets in where thermoregulation stops and the body

temperature starts to drop as the brain can no longer maintain the homeostatic feature after

death47. Therefore, the body temperature will begin to adjust to the ambient temperature of

the surroundings through convection, conduction, radiation and in the case where the subject

is wet, evaporation47. The difference between the temperature of the body at time of death

and the ambient temperature is the primary factor that affects the cooling rate, the bigger

the difference, the faster the body cools48,49. For instances, cooling rate is higher in a thin,

naked body that is immersed in water and lower in an obese and well covered body48. Due to

the cessation of thermoregulation that causes perspiration to stop, skin of cadavers is

reported to be a better substrate for development of latent prints since there is no sweat to

wash away the latent print residue46,50. The low body temperature of cadavers also solidifies

the oily substances of fingerprints, making it more durable for examinations46.

2.1.4 Human Skin as Substrate

Skin has unique characteristics that distinguish it from other surfaces investigated for latent

fingerprints. Skin possesses viscoelasticity property that allows movement and in turn

provides protection against injury as it is able to return to its baseline without breaking51,52.

The movement of the skin can cause possible distortion to the latent prints deposited on the

skin and fingerprints can be preserved longer when there isn’t any movement that causes the

skin to stretch. Besides that, the recovery rate of latent fingerprints also depends on the area

of deposition on the body and the condition of the skin at that respective area. In a laboratory-

controlled study, fingerprints were only deposited on straight and smooth skin surfaces while

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hairy, damaged and heavily wrinkled areas of the body are avoided53,54. These features can

potentially damage or distort the latent prints by causing the formation of a partial

impression. Furthermore, latent fingerprints left on dead bodies may also be affected by

postmortem changes such as putrefaction that starts around the fourth day after death. And

according to a study conducted by Baran (2009) on pig skin, powdering was no longer useful

on skin surface when bloating of the body begins55. Singh (2020) suggested that in cases with

putrefied bodies, contactless techniques like ALS, fuming, photography etc can be more

effective than powdering although the recovery rate may not be as successful56. In addition,

investigators should be extra cautious when transporting and examining cadavers that are

going through the autolysis stage because the skin is extremely fragile and skin slippage can

cause the loss of potentially valuable fingerprint evidence.

2.2 Recovery Techniques

Determination of the most effective fingerprint detection and recovery method is often

dependent on several factors like the nature of the surfaces, environmental conditions and

presence of contaminants. The varying types of surface are namely porous, semi-porous, non-

porous, rough or smooth surfaces. Porous surfaces like skin, paper and cardboard are

absorbent, non-porous surfaces such as glass, metals and plastics are not and semi-porous

surfaces like glossy paper, finished woods and cellophane tapes are able to absorb and resist

substances deposited. It is extremely important to identify the various types of surfaces

before application of any reagent as mistreating the fingerprints would result in loss of

evidence with extremely high evidential value. Skin has always been a challenging substrate

for latent prints development due to its many unique characteristics but over the decades,

researchers have studied the effectiveness of some powdering and fuming techniques.

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2.2.1 Powdering methods

Fingerprint powders are applied by brushing onto the surfaces where latent fingerprint

impressions are suspected to be located. The powders work by mechanically adhering to the

oil and sweat components of fingerprints. There have been many successful attempts where

researchers recovered latent fingerprints from human skin and pig skin.

The most commonly used fingerprint powders are the magnetic black, Swedish black and

black fingerprint powders. Farber and her colleagues performed an experiment on the

smooth and undamaged parts of the limbs of 40 cadavers54. In their study, magnetic powder

was found to be the better adhesion agent and produced excellent results when used in

combination with Isomark© lifters. The authors stated that lifting the fingerprints helped

improve the negative dactyloscopic results to either elimination or positive identification.

Similarly, a study conducted by Baran (2013) on pig skin discovered that the magnetic jet black

was very effective as the developed latent fingerprints showed third level ridge details55. The

author also reported that developed fingerprints of comparison quality began to deteriorate

after the 43rd hour and fingerprints were unidentifiable when the temperature of the skin

reached 48oC as putrefaction started to set in55.

In another research carried out by Trapecar and Balazic where living subjects and cadavers

were used, it was reported that black magnetic powder and Swedish black powder yielded

good quality prints with identification potential from the skin of living subjects but only

managed to recover a limited amount of ridge details from the skin of cadavers which

contradicts the findings from Farber and her colleagues, and Baran57. The Swedish black

powder has been proven in multiple studies to have produced promising results57,58,53.

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However, the results it produced is also dependent on the lifters used. For instance, a

research studying the best fingerprints lifters to be used together with Swedish black powder

found that fingerprints that were lifted with white fingerprint gelatine and silicone lifters

produced fingerprints with clear ridge details while poor results were obtained with white

instant lifter and adhesive tape58. Other fingerprint powders such as magnetic silver, silver

special, lightning grey and lightning white powders yielded blurry fingerprints that are not

suitable to be used for further comparison57,55. Although these techniques had been proven

to be effective in the recovery of latent fingerprints from both human and pig skin, there are

also a number of other factors such as skin conditions, postmortem changes, environmental

conditions, external contaminants etc. that affect the effectiveness of these techniques.

2.2.2 Fuming Methods

i. CA fuming

Latent fingerprints development from human skin with cyanoacrylate (CA) esters has been

tested by researchers and has proven to give satisfactory results in some cases under certain

conditions. The mechanism of CA fuming is the heating of acrylate resins in the presence of

water causes it to vaporize and interact with the fingerprint residues and produce a white

solid called polycyanoacrylate59. The success rate of CA fuming on skin is highly dependent of

several important variables that includes moisture and temperature of the skin, and fuming

time60. Generally, this technique does not yield good results when used on moist or cooled

cadavers57,60. Moisture on the skin can be a result of condensation that occurs when

refrigerated bodies are being placed in environment that has higher ambient temperature.

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According to a research conducted by Trapecar and Balazic (2007), cyanoacrylate fuming that

was performed between 0 minute to 30 minutes after the bodies were removed from the

cooler failed to recover any fingerprints from the skin of five cooled cadavers due to

condensation on the skin surface57. It was recommended that bodies should be left out for a

longer period of time i.e. at least 4 hours to allow the moisture to completely dissipates prior

to treatment54.

Besides that, Delmas hypothesised that the residual body heat and moisture of cadavers may

be another factor that affects CA fuming61. In that study where fingerprints were treated with

CA fumes and then dusted with a mixture of black magnetic powder and Rhodamine 6G, it

was observed that bodies processed sometime between 12 to 36 hours post-mortem

required supply of warm and moist air to the dusted fingerprints for visualisation and no

moisture was required for bodies processed within 10 hours of being deceased61. The author

assumed that the bodies that have been deceased longer which means lower residual

temperature and moisture requires external supply of warmth and moisture to activate the

dusting agent. However, there is no further evidence to support the author’s assumption.

Another factor to be taken into consideration is the fuming time. Studies have been

conducted to identify the most optimal fuming time for skin but most of these studies have

reached contradictory conclusions. Some researchers suggest longer fuming time, and some

suggest extremely short fuming time. According to Furtell (1996), the Knoxville Department

police specialist built a portable glue fuming chamber and researchers obtained fingerprints

by applying cyanoacrylate to the skin for 10 to 15 seconds62,63. On the other hand, a study

that used fuming time of 30 minutes yielded unsatisfactory results due to condensation and

low skin temperatures57. There are also cases where better results were obtained when

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longer fuming time was utilised. For instance, in an experiment conducted by Fortunato and

Walton, it was discovered that fuming time of 60 minutes produced latent fingerprints with

the best quality60,64. Case study conducted in the field had also reported that best results were

obtained when a murder victim was exposed to CA fuming for 80 minutes60,65. In summary,

literature findings regarding the optimal fuming time for the development of latent

fingerprints on skin are irregular. This issue had prompted William R. King to conduct a study

to determine whether the fuming time has any effect on the quality of developed fingerprints.

In his study, King tested fuming times between 10 to 125 minutes and reported that no

significant relationship was found between the quality of recovered fingerprints and fuming

time60. However, this study was conducted where variables including the quality of

fingerprints of different individuals, body temperature and humidity, time between

fingerprint deposition and CA fuming, and presence of background sweat during deposition

were controlled. King did not exclude the possibility that different outcomes might be

obtained if these variables were manipulated60.

ii. Ruthenium Tetroxide (RTX)

The Ruthenium Tetroxide (RTX) solution, similar to the cyanoacrylate, develops latent

fingerprints through fuming. RTX fumes react with organic compounds in the fingerprint

residue and turns them into dark coloured solids but unlike cyanoacrylate, it is safe to be used

on human skin. A study conducted by Trapecar and Balazic (2007) using RTX developer on

cooled cadavers resulted in fingerprints with clear ridge details and are potentially

identifiable57.

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iii. Iodine Fuming – Silver Plate Transfer

Iodine fuming is one of the oldest techniques used to develop latent fingerprints on skin. This

method works by vaporizing the iodine crystals into violet-brown fumes that reacts with fatty

acids and moisture, turning the latent fingerprint dark brown66,67. Results obtained by iodine

fuming is not permanent due to its sublimation, but developed prints can be fixed with

chemicals such as 7, 8-Benzoflavone or even 1% starch solution67-69.This method was most

effective when used on cooled cadavers and least effective when used on live skin because

of the constant secretion; latent prints with identifiable characteristics were recovered from

cooled cadavers up to 72 hours post deposition while no useful fingerprints were recovered

from live body after the first hour46.

2.2.3 Direct Transfer Method

Enhancement of latent fingerprints can be done either prior or after lifting. Latent fingerprints

on human skin can be lifted prior to development by using a Kromekote card, pressing it

directly on top of the impressions56,70. This method needs to be carried out extra carefully to

prevent slippage and damage of the latent print impression. Once lifted, the card can be

treated with fingerprint powders to enhance the latent impression. A study showed that this

technique was able to lift prints from living subjects for up to 1.5 hours after deposition and

on cadavers, it should be carried out before they are being refrigerated56,70. Sampson &

Sampson reported that substrates such as bond paper, copy paper and computer paper have

worked well in studies and have also been successful in the field71. It was also noted that in

some occasions, best results may come from performing two sequential direct transfer as the

first lift may remove excess moisture from the skin71. The authors suggested that the transfer

medium be heated prior to application if the surface of the skin is cold and avoid applying the

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transfer mediums with bare hands as this would result in the development of incomplete

ridge details.

2.3 Recovery of Touch DNA from Treated Fingerprints

2.3.1 Techniques used in the recovery of touch DNA from latent fingerprints

DNA sampling can be beneficial when recovered latent prints are uninterpretable or the

fingerprints are not registered. Under such circumstances, obtaining DNA profiles from

fingerprints may assist in linking DNA traces from other crime scenes through database

searching22. Since swabbing for DNA from latent fingerprints damages the fingerprints and

reduces its quality72, the forensic workflow usually requires DNA to be sampled after latent

prints development. Studies where DNA was sampled after the development of fingerprints

and simultaneously have been conducted over the years. The most commonly used technique

by researchers is swabbing but there is also other equally useful and possibly more effective

technique called direct extraction.

As the transfer of DNA from one individual to another highly depends on the ‘shedding’ ability

and the intensity of contact process, it is extremely crucial for investigators to obtain as much

DNA as possible which makes the extraction protocol important. The swabbing method may

result in loss of DNA as it requires transferring cells from skin to lifters, then to the swabs for

extraction. On the contrary, direct extraction method where the fingerprint lifters containing

lifted latent prints are homogenized and treated can minimize the loss of DNA. Although not

conducted on human skin, a study conducted by Zieger et al. where the efficacy of swabbing

and direct proteolytic digestion was compared showed that direct extraction is the more

effective method22. The authors reported that higher percentage of total DNA were detected

from the direct extraction of the transparent gelatine lifter used. In addition, it was also

27

reported that at least 80% of the touch DNA originated from the fingerprint was transferred

onto the lifter but this may be different if the surface is rough and textured22. The drawback

of the direct extraction technique is that DNA and inhibitor-free lifters are currently

unavailable in the market. The authors reported that small amount of DNA was detected from

the negative controls extracted by direct proteolytic method while no DNA was detected from

the swabbing method; high quality DNA was not obtained by directly digesting BVDA’s black

and white gelatin lifters and it was assumed that they contain inhibitors22.

Researchers have also investigated the quality of latent fingerprints subsequent to DNA

recovery. Fieldhouse and her colleagues conducted an experiment where five DNA recovery

techniques i.e. dry swab, wet swab, flocked swab, gel lift and tape lift were tested on glass,

metal, paper, plastic and glossed wood before developing the latent prints19. The authors

observed that the extent of destruction is highly dependent on the type of surface the latent

fingerprints are deposited on. Latent fingerprints on textured surfaces such as plastic and

glossed wood are less prone to damage because the elevated positions are more exposed

than the areas located in the troughs and therefore providing some protection where the

DNA recovery techniques do not touch72. They also reported that flocked swabs and gel lifts

are the least destructive towards the latent print impressions on all substrates except for

glass. However, the effects these methods have on skin is still unclear.

2.3.2 Effects Fingerprint Powders have on the Recovery of DNA

In addition to extraction techniques and composition of fingerprint lifters, fingerprint

powders affect the recovery of DNA as well. The particle density, solubility in water and DNA

affinity are criteria that should be taken into consideration when selecting powder20.

28

Fingerprint powders with lower particle density than water, are water insoluble and have

little affinity for DNA are ideal as it allows for the minimization of DNA losses due to powder

binding. According to Oleiwi et al., infrared fluorescent fingerprint powder specifically the

fpNatural 1TM had insignificant statistical effect on the quantity of DNA recovered from clean

glass slides20. Furthermore, black fingerprint powders were also found to have worked well

for the recovery of touch DNA not only from glass slides but also from human skin21,22,54.

Similarly, magnetic powder had been proven to have worked on both surfaces, but it was

reported to have caused more interference to the quality of the recovered touch DNA21,54.

According to Alem et al., touch DNA that was extracted from fingerprints treated with black

magnetic powder and black powder produced a higher and lower DNA mean respectively

when processed with qPCR21. However, when subjected to short tandem repeat (STR)

analysis, the results obtained from black magnetic powder were of poorer quality when

compared to the STR results obtained from black powder21. Likewise, Farber et al. observed

similar results when two extraction methods i.e. organic extraction and extraction with

NucleoSpin® Tissue XS Kit were compared54. Therefore, evidently black fingerprint powder has

less negative effect when it comes to DNA recovery of treated fingerprints, but it is still

unclear what causes magnetic powders to have more interference.

2.4 Factors affecting the durability of latent fingerprints

The durability of latent fingerprints is often affected by different environmental factors and

various post-deposition conditions. This section of the literature review will discuss how these

factors impact the durability and recovery rate of latent fingerprints.

29

2.4.1 Humidity

Humidity is how much water vapor is present in the air and it is often measured in terms of

relative humidity. Relative humidity (RH) is expressed as a percentage and it refers to the

amount of water vapor present in the air and how much it can be held at its current

temperature73. Relative humidity is one of the many variables that can affect the durability of

fingerprints. Extremely low and high humidity in the environment affect latent fingerprints by

causing dehydration or excessive moisture on the prints that will in turn yield poor quality

fingerprints upon recovery. When latent fingerprints are exposed to environment with low

humidity, the secretions tend to evaporate, and the enhancement agent will not be able to

adhere to the print. Therefore, when a latent print is too dried up, it requires to be rehydrated

prior to the enhancement step. Rehydration can be done by spraying fine mist of water,

applying steam and refrigerate the body and then move it to a warmer environment50. The

area of skin must then be dried until the moisture completely dissipates.

On the other hand, excessive moisture on skins develops when they are exposed to

environment with high relative humidity. The moisture will interfere with the adherence of

enhancement reagents to the fingerprint residue and as a prevention step, the skin may need

to be dehydrated before applying any enhancement technique. Dehydration can be done by

allowing the skin to acclimate to an air-conditioned environment or a room with appropriate

temperature and humidity levels50. In a study conducted on glass slides, it was determined

that the developed latent prints stored in a higher humidity condition appeared to be in a

worse condition when they were recovered after seven weeks17. On the contrary, latent

prints stored in lower humidity conditions showed no significant difference between the

prints developed immediately and the prints developed after seven weeks. Sampson &

30

Sampson stated that the optimum humidity levels for the recovery of latent prints from

human skin is between 40-60%50. As relative humidity varies at different countries and

locations, it is unclear how the relative humidity in Western Australia may affect the durability

of latent fingerprints on skin.

2.4.2 Temperature

Similar to humidity, ambient temperature also plays an important role in affecting the

durability and quality of latent fingerprints on skin. When an object is stored in an

environment with a certain temperature, it tends to acclimate to that temperature. For

instance, when a cadaver is stored in an environment cooler than the average surface

temperature of the skin, the skin will cool50; if stored in moderate climate, the temperature

of newly deceased bodies will drop and when it approaches the ambient temperature, the

cooling rate will slow down56. The ambient temperature does not only affect the surface

temperature of the skin, it can also cause the surface area of skin to expand or shrink and this

affects the ridge details56. Living skins however are a little different. According to Sampson

and Sampson (2005), the temperature of living skin is different at various parts of the body

and it depends on its exposure to the environment50. Fingerprints are more prone to

deterioration when expose to higher temperature and the sebaceous substituents degrades

more rapidly at higher temperature46,74.

Researchers have studied the effects temperature have on latent prints on skin and different

observations were seen. Shin and Argue (1976) reported that cadavers preserved at 4oC had

a higher recovery rate compared to living subjects because the low body temperature

solidifies the oily substances present on the fingerprints while the higher temperature of a

31

living person kept the oily substances at dispersive liquid state46. Hence, the authors

concluded that fingerprints last longer the faster the body is cooled. In actual cases where

fingerprints were recovered from skins of living victims, the successful recovery time has been

at most five hours and in all cases, the victims were in a comfortable and cooled

environment50. The authors also suggested that the area of skin where the fingerprints are

suspected to be at should be cooled before applying any techniques in order to preserve the

evidence. For dead bodies, it was reported that if the surface temperature of skin is at 32oC

or higher, the fingerprint residues will be in a liquid state and this will wash away prints54,75,76.

To overcome this problem, it is suggested that the skin needs to be chilled prior to application

of any techniques50. On the other hand, a separate study done on pig skins reported that

prints developed at 4.5oC had poor quality, prints developed at moderate temperature (21oC-

29oC) produced good quality results, and lastly no identifiable fingerprints could be developed

once the skins reached 48oC55. Nevertheless, the author noted that the results did not have a

specific pattern probably due to the locations the fingerprints were deposited.

There were also studies that concluded temperature did not have any significant influence on

the quality of recovered fingerprints. A study participated by four countries in Europe namely

Austria, Denmark, Germany and United Kingdom where the climate is generally temperate,

and the ambient temperature ranged from 17-25oC during the experiment came to

conclusion that temperature did not have significant influence on the quality of fingerprints

recovered54. Likewise, in another study conducted at California, USA by Barnett and Berger

(1977), there were no statistically significant difference between the fingerprints that were

developed immediately, and fingerprints developed after being stored at various

temperatures17. However, these studies only tested moderate temperatures ranging from

32

17oC to 30oC, which was proven in other studies to be the optimal temperatures for the

recovery of fingerprints from skin. As the results from recovery of latent fingerprints from

human skin may vary in terms of efficacy in different parts of the world where the

environmental conditions i.e. ambient temperature and relative humidity are different, it is

of great importance to find out how the environmental conditions in Western Australia affect

the latent fingerprint impressions on skin.

2.4.3 Physical contact and external contaminants

Besides the conditions of the physical environment, quality of fingerprints is also highly

dependent upon the physical contact of donors, objects, contaminants and more during and

after deposition. During deposition, it is important to take into consideration the pressure

exerted by the donor. Too much pressure causes the latent prints to smudge but too little

pressure may form partial or incomplete latent print impressions. Trapecar and Balazic

reported that 500g/in2 produced better quality fingerprints than 200g/in2 and neither skin

types nor contact time had any effect on the fingerprint quality57. Besides what happen during

deposition, physical contact between deposited latent fingerprints and other objects can also

cause damage to latent fingerprints. In addition to that, foreign contaminants may also

contribute to the changes and damages in latent prints. For instance, dust, condensation of

grease and water, traffic of the surrounding area etc. may all affect the durability of

fingerprints17.

2.4.4 Skin Conditions

Both the depositor’s and substrate’s skin conditions affect the quality of fingerprints. Skin

conditions for depositor include the age, amount and composition of eccrine and sebaceous

33

secretions, gender, rate of sweat, health, mental stress, race and more43. Individuals with dry

skin and lower rate of sweat will produce less distinct fingerprint impressions77. The sebum

composition changes as one progresses through the different stages of life14. For instances,

free fatty acid composition tends to increase in young children and stabilizes in adolescent

and post-adolescent; triglycerides decrease in infants and rise to 50% in young children and

decrease again in post-adolescent subjects14. All these factors play a role in producing

fingerprint impressions of good and distinctive quality.

Skin conditions for substrates refer to skin at various part of the body, wrinkles, wounds, hair,

secretions in living subjects, bloating in cadavers and others. Fingerprint impressions can look

different when deposited at various parts of the body. Fingerprints deposited on bonier parts

of the body produced better results than fleshy parts of the body54. This is probably due to

the sturdiness of the skin at bony areas as the bones act as a support to the skin while softer

surfaces with less support might cause fingerprints to be smudged when they are pressed

down too hard during the deposition. The area of ankle, chest, femur, shin and ulna were

found to be suitable body parts for recovering useful fingerprints53. Furthermore, wrinkles,

wounds and hair are also disruptive to the ridge details as it influences the deposition of a

complete fingerprint impression. Besides that, the constant renewal of cells and secretion in

living bodies may cause a ‘washout’ effect and putting a constraint on the recovery time46. In

non-living subjects however, there is no such effect, but the decomposition progress does

affect the fingerprints in some ways. When bloating and decomposition occur starting from

the second day after death, it could alter the ridge details of a fingerprint impression. Baran

(2009) found that fingerprints placed on bloated areas of pigs produced poor quality

fingerprints that were either blurry or not visible at all55.

34

3.0 Experimental Design

3.1 Deposition of Latent Fingerprints

Pig skin will be used as an alternative to human skin in this study as their anatomy is known

to be highly similar to that of human skin in terms of the thickness, general structure, collagen,

contents of hair follicle, pigmentation and lipid composition78. All pig skins are to be cleaned

and dried thoroughly prior to being divided into 2 groups (room temperature and

refrigerated) to remove all contaminants and latent fingerprints. Prior to the deposition of

fingerprints, ensure all pig skins are at room temperature in order to minimize the differential

effects of skin temperature and condensation. Then, label all the pig skin with numbers and

frames to indicate the deposition sites. The author’s sebaceous fingerprints will then be

deposited onto all the labelled sites at same time and this includes the fingerprints that will

later be used as positive controls during DNA analysis.

3.2 Storage Conditions

After deposition, all pig skins are to be stored in their respective storage areas (indoor and

refrigerator) while constantly monitoring the ambient temperature and relative humidity

until time for fingerprint enhancement.

3.3 Recovery of Latent Fingerprints

The latent fingerprints deposited on pig skin will be treated with magnetic black and Swedish

black powders, cyanoacrylate (CA) and iodine fuming to identify the most effective recovery

method. Treated fingerprints will then be lifted with different types of lifters namely

transparent adhesive tapes, gel lifters and silicone casting material with the purpose of

35

identifying the most suitable and effective lifters to be used in conjunction with the various

recovery methods. In addition to that, the direct transfer technique will also be tested with

the use of glossy paper and the results of the two techniques will be compared. In order to

assess the durability of latent fingerprints, treatments and lifting of the fingerprints will be

done at different time intervals (i.e. immediately, 1h, 3h, 6h post deposition). All fingerprints

will be recorded via photography before and after treatment and lifting and finally the results

will be evaluated using the Bandey scale (Table 1).

Table 1: Bandey scale – grading system for the determination of the quality of ridge detail

for developed fingerprints (79).

Grade Comments

0 No development

1 Signs of contact but <1/3 of mark continuous ridges

2 1/3-2/3 of mark continuous ridges

3 >2/3 or mark continuous ridges, but not quite a perfect mark

4 Full development – whole mark clear continuous ridges

3.4 DNA Extraction and qPCR

The recovered latent fingerprints will be subjected to DNA extraction and qPCR to assess the

effects of the recovery methods on the quantity of touch DNA recovered. The lifted

fingerprints will be swabbed immediately after treatment and photograph, and DNA

extraction will be done according to the manufacturer’s protocol and the amount of touch

DNA recovered will be measured by performing qPCR. The results of the qPCR are quantitative

(ng/μL) and a student t-test will be conducted to determine if there is any significant

36

difference between the quantity of touch DNA recovered from the control and treated

groups.

4.0 Experimental Aims and Hypothesis

From the literature findings, it is evident that the quality and longevity of latent fingerprints are

influenced by a number of factors including physiological factors such as quality of fingerprints during

deposition and skin conditions, and also surrounding physical conditions namely temperature,

humidity and environmental contaminants. Subsequently, the quality and durability of latent

fingerprints vary in different parts of the world and this necessitates a study to be conducted in Perth,

Western Australia in order to examine the durability of latent fingerprints specifically on pig skin when

exposed to the local weather condition. Besides that, this research also aims to identify the most

effective recovery method to be used on skin and their effect on the recovery of touch DNA from

treated latent fingerprints. These can be achieved by treating pig skins with different fingerprint

powders and chemicals that are recommended within the scientific literature at different

time intervals and by assessing the effects of the optimised latent fingerprint technique on

the recovery of human DNA post-treatment using qPCR.

Experimental Hypothesis 1

H0: latent fingerprints deposited on skin has longer durability when stored in environment

with low ambient temperature.

H1: latent fingerprints deposited on skin has shorter durability when stored in environment

with low ambient temperature.

37

Experimental Hypothesis 2

H0: latent fingerprint recovery method has no effect on the quality of the fingerprint and

quantity of recovered DNA.

H1: latent fingerprint recovery method reduces the quality of the fingerprint and quantity of

recovered DNA.

5.0 Conclusion

Fingerprints are an important source of evidence that can be found at crime scenes. On top

of being used for identification through the comparison of ridge details, it can also be used

for identification through DNA analysis. Thus, it is extremely important for forensic

investigators to retrieve these evidences without causing any irreparable damages.

Consequently, many fingerprints recovery techniques have been studied and investigated

over the years and reviewing and analysing available literature allows deeper understanding

on the effectiveness of the different techniques and the varying factors that affect them.

Among the many substrates where fingerprints can be recovered from, skin is one of the most

challenging one. However, over the past few decades, researchers have managed to identify

many effective techniques such as physical development with fingerprint powders, chemical

fuming and direct transfer methods. Experiments have also been conducted to investigate

the possibility of human DNA recovery from powdered fingerprints and discovered that some

dactyloscopic powders interfere with DNA recovery more than others. These latent

fingerprint recovery techniques are useful but not without any challenges. The available

literatures have shown that the success rate of recovering latent fingerprints from skin often

depends on the quality of prints, skin conditions, environmental conditions and

contaminants. Therefore, the results from recovery of latent fingerprints from skin may vary

38

in different parts of the world. Research on this matter had been conducted in many

countries but it is still unclear how the Mediterranean climate in Perth, Western Australia will

affect the latent fingerprints deposited on skin and subsequently the effectiveness of the

recovery techniques. The findings of this study will determine the effects physical conditions

i.e. ambient temperature and relative humidity in Perth, Western Australia have on the

durability of latent fingerprints on skin and assist forensic investigators in decision-making

when selecting recovery techniques for latent fingerprint development on skin.

39

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difference/.

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74. Johnston A, Rogers K. The effect of moderate temperatures on latent fingerprint

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Live Subjects and 23 Cadavers. J Forensic Identif [e-journal]. 1994 [cited 2020 Dec 3];

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76. Wilkinson DA, Watkin JE, Misner AH. A comparison of techniques for the visualisation of

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or_the_visualization_of_fingerprints_on_human_skin_including_the_application_of_io

dine_and_a-naphthoflavone.

77. Rohrig B. Guilty or innocent? Fingerprints tell the story. Slide Legend [Internet]. 2016

[cited 2020 Dec 29]. Available from: https://slidelegend.com/guilty-or-innocent-

fingerprints-tell-the-story_5a57dae71723dd39295625b5.html.

78. Summerfield A, Meurens F, Ricklin ME. The immunology of the porcine skin and its value

as a model for human skin. Mol Immunol [Internet]. 2014 [cited 2021 Feb 19]; vol(66):

14-21. Available from:

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79. Bandey HL, Gibson AP. The powders process, study 2: evaluation of fingerprint powders

on smooth surfaces. Home Office Scientific Development Branch [Internet].

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_Evaluation_of_Fingerprint_Powders_on_Smooth_Surfaces_08-06.pdf.

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Part Two

Manuscript

Identification of the Optimum Latent Fingerprint Recovery Method from Pig Skin at

Varying Temperatures

51

Abstract

Fingerprints are known to be extremely important in criminal investigations due to their

uniqueness. Human skin is one of the most challenging surfaces for latent fingerprint recovery

but can be extremely beneficial as physical contact between perpetrators and victims are very

common. This study investigated the effect of temperatures on the effectiveness of certain

development techniques. Piglets were used as substrate to replace human skin as they are

known to have highly similar structures. Two fingerprint powders namely Black Magnetic,

Swedish Black and two other methods cyanoacrylate (CA) fuming and direct transfer with

glossy inkjet photo paper were used because studies have determined them to be effective.

The piglets were stored in 4°C, 24°C and 37°C for two hours before being treated with the

different methods. Fingerprints treated by powdering and CA fuming were then lifted with

three different lifters (transparent gel, instant white, Silmark white) to assess their

effectiveness when used in conjunction with the two methods. Powdering and CA fuming

managed to develop prints with visible ridge details of varying darkness and clarity while

direct transfer failed to recover any print. Temperature was found to have minor effect on

some of the development techniques; low temperature appeared to have solidified the

fingerprint residues rendering the direct transfer method ineffective while higher

temperature kept the prints at a dispersive liquid state, making it easier to be transferred and

easier for CA fumes to adhere to. Powdering however was not affected by the temperature

as both powders managed to enhanced prints with ridges of different clarity. Black magnetic

powder was found to be the better adherent in powdering method while Swedish black

powder produced better results in CA fuming. Silmark white was determined to be the best

lifters among all three lifters tested. Further research on the effects of the methods and lifters

52

tested on subsequent DNA recovery should be undertaken to find out if there is any inhibitory

effect.

Keywords: latent fingerprints, pig skin, temperatures, powdering, cyanoacrylate, direct

transfer

53

Table of Contents:

Abstract……………………………………………………………………………………………………………………..…….. 51

List of Figures……………………………………………………………………………………………………………..……. 54

List of Table………………………………………………………………………………………………………………………. 54

List of Abbreviations……………………………………..…………………………………………………………..…….. 55

1.0 Introduction…………………………………………………………………………………………………………........ 56

2.0 Materials and Methods…………….………………………………………………………………………………… 61

2.1 Preparation of Piglets..……………………………………………………………………………………......... 61

2.2 Fingerprint Deposition……………..………….………………….……………………………………………… 61

2.3 Storage Conditions……………………….………….………………….………………………………………….. 62

2.4 Development and Enhancement of Latent Fingerprints…………………………………………. 62

2.4.1 Direct Transfer accompanied by Powdering.…………….……………………………………. 62

2.4.2 Powdering on Skin.……….………………….…………………………………………………………….. 63

2.4.3 Cyanoacrylate fuming accompanied by Powdering on Skin.……………………………. 63

2.5 Assessments of Lifters……………………………………..……………………………………………………… 64

2.6 Presentation of Results…………………………………………..………………………………………………. 64

3.0 Results and Discussion…..…………………………………………………………………………………………….65

3.1 Development of Fingerprints………..…………………………….……………………………………………65

3.1.1 Direct Transfer + Powdering….……………….…………………………………..……………………65

3.1.2 Powdering on skin.……….………………….……………………………………………..……………….67

3.1.3 Cyanoacrylate fuming + Powdering on Skin..…….………………………………..……………70

3.2 Effectiveness of Lifters………..………….………………….………………..…………………………………..73

3.2.1 Gel Lifters………..………….………………….……………………………………………………………….73

3.2.2 Instant Lifters………..………….………………….………………………………………………………….74

3.2.3 Silmark White.………..………….………………….…………………………………………………………75

4.0 Limitations and Future Studies………..………….………………….…………………………………………..76

5.0 Conclusion….……………………………………..…………………………………………………………………………77

6.0 Reference List..….…………………………………………………………………………………………………………79

7.0 Appendices….……………………………………..……………………………………………………………………….82

54

List of Figures

Figure 1. Diagram showing the deposition of latent fingerprints with each fingertip in a series

of three dilution………………………………………………………………………………………………………………….62

Figure 2. Alignment of lifters used on the different sets of prints developed by powdering and

CA fuming. …………………………………………………………………………………………………………………………64

Figure 3. Fingerprints treated with black magnetic and Swedish black powders…………………70

List of Tables

Table 1. Bandey grading system used for the analysis of fingerprints quality.……………………..65

Table 2a. Summary of results for transfer medium treated with black magnetic powder……..65

Table 2b. Summary of results for transfer medium treated with Swedish black powder……..65

Table 3a. Summary of results for skin treated with black magnetic powder.………………………..67

Table 3b. Summary of results for skin treated with Swedish black powder.………………………….68

Table 4a. Summary of results for CA fumed prints treated with black magnetic powder………70

Table 4b. Summary of results for CA fumed prints treated with Swedish black powder………..71

Table 5. Summarised results for treated prints lifted with transparent gel lifters……………….73

Table 6. Summarised results for treated prints lifted with instant white…………………………….74

Table 7. Summarised results for treated prints lifted with Silmark white……………………………75

Appendix 1. Grades given for the latent prints treated with different methods…………………82

55

List of Abbreviations

CA Cyanoacrylate

POI Person of interest

ALS Alternative light source

RH Relative humidity

DNA Deoxyribonucleic acid

56

1.0 INTRODUCTION

Fingerprints are valued evidence used in criminal investigation. Fingerprints are being used

for the purposes of victim identification, and in placing persons of interest (POI) at the scene

of crime or exonerating them. Fingerprint impressions are made from the natural secretions

of the human body in combination with environmental contaminants and are often left on

anything the fingertips come in contact with. Patent and plastic impressions are immediately

visible to the human eye while latent impressions require additional enhancement techniques

for the visualisation. Latent print impressions are made up of body secretions like lipid, sweat

and external contaminants that covers the ridges upon deposition1. They can be found on all

kinds of porous and non-porous surfaces. Recovery is much simpler on non-porous surfaces

than on porous surfaces because porous surfaces are more textured and tend to absorb

substances deposited on them2.

The process of recovering fingerprint impressions is a complex one as some prints may require

multiple treatments to clearly visualise the ridge details. Various techniques have been

developed over the years and are currently in use by forensic experts for the detection and

recovery of fingerprint impressions. These methods are namely the optical, physical, and

chemical techniques. Optical method refers to the use of alternative light sources (ALS) and

are usually used prior to any other enhancement techniques as it allows investigators to

detect and locate the latent print without risk of damaging the print. This non-intrusive

method is then followed by physical or chemical methods where fingerprint powders and

chemicals such as cyanoacrylate, iodine, ninhydrin, and more are used to enhance the prints.

Selection of the most appropriate technique is often dependent on the type of surface latent

fingerprints are located on.

57

Among the many types of surfaces, human skin has been found to be one of the most

challenging to recover latent fingerprint from due to its many physiological reasons3. For

instance, the constant renewal and regeneration of skin cells, elasticity of skin, the regulation

of body temperature, environmental impacts on skin etc.3. However, to be able to recover

fingerprint from skin is of great importance as physical contact between a perpetrator and

the victim is almost unavoidable. Research has been conducted in an attempt to successfully

recovery latent prints from skin but most of the techniques studied were only effective when

used under ideal laboratory conditions2. Some studies had successfully recovered fingerprints

with potential for identification by utilising techniques such as ALS, powdering, chemical

fuming, direct transfer, electronography, laser detection and x-ray4.

In separate studies carried out by Farber et al. and Baran on cadavers and porcine skin

respectively, the researchers came to the same conclusion that black magnetic powder was

the better adhesion agent as it yielded good results that has the potential to be used for

identification5,6. Farber et al. also stated that lifting the prints with silicone lifter improved the

negative results to either positive identification or elimination5. On the contrary, in another

study conducted on living persons and cadavers using Swedish black and black magnetic

powders, Trapecar and Balazic reported that good quality prints were obtained from skin of

living persons but not of cadavers3. In addition to that, there are also other studies that found

that Swedish black powder is effective and can produce good results3,7,8. The final result of

the enhancement process is also reliant on the types of lifters used. White gelatine and

silicone lifters were proven to be the most appropriate lifters to be used on fingerprints

powdered with Swedish black powder7.

58

Besides powdering techniques, chemical methods have also been studied. One of the most

common methods is cyanoacrylate (CA) fuming but this technique is easily affected by

external factors such as the temperature and humidity of the skin, and fuming time9. CA

fuming does not work on moist or cooled skin and therefore it is recommended that skin

should be allowed to air dry completely prior to fuming3,5,9. Studies have also shown

contradictory results when it comes to determining the optimum fuming time. Positive results

have been obtained from studies that have recommended extremely short fuming time i.e.

10 to 15 seconds and extremely long fuming time i.e. 60 and 80 minutes9-12. However, in a

study conducted by King where variables such as body temperature and humidity, time

between deposition and treatment, presence of background sweat during deposition and

quality of fingerprints of different individuals was controlled, the author reported that there

was no significant relationship between the quality of recovered fingerprints and fuming

time9.

A similar but less explored chemical reagent called Ruthenium Tetroxide (RTX) solution which

is safe to be used on human skin was tested by Trapecar and Balazic on cooled cadavers3.

Unlike CA fuming, RTX was able to produce fingerprints with clear ridge details that are

potentially identifiable3. Likewise, iodine fuming is also a method that worked well on cooled

cadavers. However, iodine fumed fingerprints fade over time and therefore requires an

additional step where chemical such as 7, 8-Benzoflavone is applied to permanently fix the

fingerprints14.

Other than applying lifters on fingerprints post-treatment, latent fingerprints can also be

lifted pre-treatment. This was successfully carried out with a Kromekote card by pressing it

59

directly onto the latent impressions4,15. Sampson and Sampson also reported that substrates

like computer paper, copy paper and bond paper was effective in laboratory setting and in

the field16. The substrates are usually dusted with fingerprint powder afterwards to enhance

the latent impressions. There is also report that best results may be obtained by doing two

consequent lifts as the first lift may aid in removing excess moisture from the skin16. This

method however is challenging because the lifters move around easily and can damage the

latent print impressions.

Another reason that causes the recovery of latent fingerprints from skin to be such a

challenging process is the durability of latent fingerprints. The durability is impacted by the

various environmental factors and post-deposition condition. Environmental factors such as

relative humidity (RH) and temperature affect not only the durability but also the quality of

recovered latent prints. Low RH tends to cause the prints to evaporate while high humidity

causes development of excess moisture on the skin that can interfere with the adherence of

enhancement reagents. On the other hand, ambient temperature can change the skin

temperature and condition by making the skin expand or shrink as the temperature changes

and this could alter the ridge details4. Besides that, the sebaceous constituents in fingerprints

are more vulnerable and degrade more rapidly when expose to higher temperature, hence

shortening the longevity of the fingerprints17,18. Additionally, the quality of fingerprints is also

affected by physical contact of donors during and post-deposition. Excessive pressure during

deposition can cause fingerprint impressions to smudge and insufficient pressure may result

in incomplete transfer of latent prints. It is impossible to determine the optimum pressure to

be exerted during deposition as it varies depending on the type of surfaces. Furthermore,

60

physical contact by foreign objects or contaminants like water, grease, dust etc. may also alter

or damage the latent prints.

Finally, the donor’s and receiver’s skin conditions play a crucial role as well. Some people

produce very distinct and excellent quality fingerprint impressions, and some do not. It all

depends on factors such as age, gender, lifestyle, diet, health, race, the amount and

composition of their secretions and more19. The parts of body where a fingerprint is deposited

on also affects the outcome. Fingerprints do not go well onto wounded, wrinkled or hairy

skin. It is also difficult to recover latent prints from soft and fleshy parts of the body. Most

importantly, the constant regeneration of cells and secretion in living bodies can cause the

latent prints to be washed out.

There has not been a study on the recovery of latent fingerprints from skin conducted in

Perth, Western Australia. This study will contribute to forensic science to determine the

possibility of recovering latent fingerprints from skin in the environmental conditions

experienced in Perth. Because pig skin has highly similar epidermal layer as human skin20,

piglets were chosen as substrate and were subjected to three different temperatures that

mimicked the Western Australia climate and treated with the powdering, cyanoacrylate (CA)

fuming and direct transfer methods. These methods were chosen because they have been

proven to be the most effective in recovering latent prints from human skin in several

research3,5-9,21. The aim of this study is to determine the effectiveness of the different

development techniques on fingerprints exposed to different temperatures. In addition to

that, three types of lifters were also tested in this study to determine their effectiveness when

61

used in conjunction with the different recovery techniques. The hypothesis investigated was

the effectiveness of recovery techniques will not be affected by temperature.

2.0 Materials and Methods

2.1 Preparation of piglets

Pigs are known to have similar epidermal characteristics as human and were therefore chosen

to be used as an alternative to human skin in this experiment20. Piglets that had died in utero

were used in this study. Prior to depositing latent fingerprints on the skin, the piglets were

shaved to remove bristle which would interfere with the transferring of latent fingerprints

onto the skin. In addition to that, they were also cleaned and washed with soap and rinsed

with water to remove dirt and contaminants that could potentially obstruct the deposition.

Once shaved and cleaned, the piglets were dried with paper towels and left out overnight in

room temperature (between 16-20°C) in a lateral lying position. Nitrile examination gloves

were worn throughout the whole process to ensure that the skin was clean and free of any

latent fingerprints.

2.2 Fingerprint Deposition

The author’s own fingerprints were used in this experiment. Three piglets were used for each

temperature and the numbers of fingerprints deposited onto each piglet vary depending on

the method (discussed in 2.4). Firstly, grids were drawn across the body to indicate the

locations of the latent fingerprints. Prior to the deposition, fingertips were rubbed against the

scalp and forehead to collect natural sebaceous secretion. Fingertips were then pressed

against the skin of the piglets, each finger in a series of three dilution.

62

Figure 1. Diagram showing the deposition of latent fingerprints with each fingertip in a series

of three dilution.

2.3 Storage conditions

To determine the most effective fingerprint recovery technique for fingerprints subjected to

different temperatures, the piglets were stored in various temperature of 4°C, 24°C and 37°C

at 60% relative humidity for 2 hours before the development process. The temperatures and

low humidity were chosen to mimic the Mediterranean climate in Western Australia.

2.4 Development and Enhancement of Latent Fingerprints

2.4.1 Direct Transfer accompanied by Powdering

Direct transfer was done by using the Krisp 180gsm 46 Glossy Inkjet Photo Paper, cut into

small pieces fit for only one fingerprint to avoid damaging fingerprints adjacent to the target

print. The transfer medium was chosen as it was mentioned in Sampson and Sampson’s paper

that photo paper and inkjet paper have worked well16. To lift the latent fingerprints, the glossy

side of the photo paper was placed directly onto the latent fingerprint and a sponge was used

63

to apply light to moderate pressure (approx. 500g – 700g) across the entire paper, as

suggested by Sampson and Sampson16. The photo papers were then left in room temperature

for 2 hours before being powdered with both black magnetic and Swedish black powders in

attempt to enhance and visualise the lifted fingerprints. 1 set of fingerprints (3 prints) were

required for each of the powder. All outcomes were then recorded with a Nikon camera.

2.4.2 Powdering on Skin

The powders used in this study were the black magnetic and Swedish black powders as they

were proven to be effective for the recovery of latent fingerprints on skin3,6. Each of the

powders were applied directly onto 3 sets of latent fingerprints (refer to Figure 2) deposited

on the skin with a DNA free fibreglass brush. The prints were then photographed with a Nikon

camera for scoring purposes.

2.4.3 Cyanoacrylate Fuming accompanied by Powdering on Skin

To develop fingerprints with CA fuming, a makeshift fuming chamber was built with an Ezy

Storage Ultimate storage tub equipped with a fan to ensure even fuming. The cyanoacrylate

used was from the Loctite Superglue. The fuming process was accelerated by heating up the

superglue with a tealight candle. As stated by King in his study, fuming time does not have

any effect on the successful development of fingerprints on skin, hence the fuming time was

set at 5 minutes9. Similar to the powdering method, a total of 6 sets of latent prints were

needed for this technique. After the fuming process, the CA developed prints were powdered

with black magnetic and Swedish black powders (refer Figure 2), and results were recorded

with a Nikon camera.

64

2.5 Assessments of Lifters

To study the effectiveness of the three different lifters, fingerprints developed by powdering

and CA fuming were lifted with the Silmark white, instant white and transparent gel lifters, all

purchased from BVDA. Each of the lifters were applied to the developed prints as shown in

the diagram below (Figure 2) and results were photographed with a Nikon camera.

Figure 2. Alignment of lifters used on the different sets of prints developed by powdering and

CA fuming.

2.6 Presentation of Results

The experiment was carried out in duplicate on the other side of the piglets. Results were

recorded as Trial a and Trial b in Tables 2 - 4. Quality of the fingerprints before and after being

lifted was assessed accordingly with the Bandey Five-Point System by analysing the clarity of

the ridge details.

65

Table 1: Bandey grading system used for the analysis of fingerprints quality22.

Grade Comments

0 No development

1 Signs of contact but <1

3 of mark continuous ridges

2 1

3 -

2

3 of mark continuous ridges

3 >2

3 or mark continuous ridges, but not quite a perfect mark

4 Full development – whole mark clear continuous ridges

3.0 Results and Discussion

3.1 Development of Prints

3.1.1 Direct Transfer + Powdering

Table 2a: Summary of results for transfer medium treated with black magnetic powder.

Black Magnetic Powder Temperature

(°C) Trial

Total Sample Number

Number of Fingerprints Graded

0 1 2 3 4

4 a

6 3 0 0 0 0

b 3 0 0 0 0

24 a

6 1 2 0 0 0

b 3 0 0 0 0

37 a

6 2 1 0 0 0

b 3 0 0 0 0

Table 2b: Summary of results for transfer medium treated with Swedish black powder.

Swedish Black Powder Temperature

(°C) Trial

Total Sample Number

Number of Fingerprints Graded 0 1 2 3 4

4 a

6 3 0 0 0 0

b 3 0 0 0 0

24 a

6 2 1 0 0 0

b 3 0 0 0 0

37 a

6 3 0 0 0 0

b 3 0 0 0 0

66

The scores appointed to the transferred prints treated with both black magnetic and Swedish

black powders did not differ much. At 4°C, a score of 0 was graded for all of the fingerprints

as no development was seen on the transfer medium. Although better results were obtained

from the prints lifted from 24°C and 37°C where a score of 1 was given to 4 of the transferred

prints, however, they were just very faint signs of contact with no fingerprint outline. This

phenomenon could be caused by the temperature. At 4°C the fingerprint residue on the skin

might have been solidified by the low temperature and prevented it from being lifted. While

the prints kept at 24°C and 37°C remained at their natural liquid state, making it easier to be

transferred. The success rate may be improved by leaving the samples in room temperature

until it gets warmer, and the prints are back to its liquid state. In addition to that, it was also

recommended that the transfer medium be heated prior to applying it onto the skin16.

Besides ambient temperature, factors such as pressure during the transfer process, transfer

medium, condition of skin, and body parts might have affected the success rate as well. Firm

pressure was not recommended when attempting to transfer untreated latent fingerprints

from one surface to another as it can cause damage to the latent prints on the substrate. This

was taken into consideration hence moderate pressure was exerted in this study, but nothing

except for some smudges was visible on the transfer medium. The piglets were powdered

with black magnetic powder after the transfer process to visualise the impressions left on the

skin; the only characteristic visible for all the powdered prints was smudged outline of the

fingerprints with no ridge detail. The moderate pressure (66approx. 500g-700g) exerted

during the transfer process might have smudged the latent fingerprints thus lighter pressure

is recommended for future studies. Furthermore, the natural anatomy of the piglets where

some parts of the body are flat and even while some parts are rugged and lopsided added to

67

the difficulty of performing direct transfer. Holding the transfer medium steadily while

applying even pressure across it was difficult to do on piglets; although the transfer process

was performed carefully, slippage or movement of the transfer medium was difficult to avoid,

and this may have caused smudging of the fingerprint impressions. The final reason that

resulted in the negative outcome could be that the glossy inkjet photo paper is not the

appropriate transfer medium to be used on skin.

Lastly, the scoring in Table 2a and 2b also showed that black magnetic powder appeared to

be the better adherent for the glossy photo paper. Although not graded, this was evident

when the visibility of the fingerprint impression on the transfer medium powdered with

Swedish black improved from no development to minimal signs of contact when dusted with

black magnetic powder. As conventional powders i.e. Swedish black powder unlike magnetic

powders, are not designed to be used on porous surfaces like papers23, this explains the result

obtained. The application of Swedish black powder with fibre brush might also rub off the

small amount of ridges lifted; the magnetic wand allows the iron powder to lightly touches

the surface, minimizing the contact and lowering the risk of damaging the prints.

3.1.2 Powdering on Skin

Table 3a: Summary of results for skin treated with black magnetic powder.

Black Magnetic Powder

Temperature (°C)

Trial Total Sample

Number Number of Fingerprints Graded

0 1 2 3 4

4 a

18 0 7 2 0 0

b 0 4 5 0 0

24 a

18 0 8 1 0 0

b 0 3 5 1 0

37 a

18 0 4 2 3 0

b 1 4 3 1 0

68

Table 3b: Summary of results for skin treated with Swedish black powder.

Swedish Black Powder Temperature

(°C) Trial

Total Sample Number

Number of Fingerprints Graded 0 1 2 3 4

4 a

18 0 8 1 0 0

b 0 3 5 1 0

24 a

18 0 8 1 0 0

b 0 9 0 0 0

37 a

18 0 6 0 3 0

b 0 7 2 0 0

Black magnetic powder was found to be a good enhancement agent to be used on skin. It

worked well on textured skin as it was easier to control and did not cause over powdering.

On the other hand, Swedish Black powder worked less satisfyingly. It adhered well to the skin

but did not work well on textured skin as the powder gets caught up very easily in the skin

texture. Most of the fingerprints were graded 1 (Table 3b) because they were over-powdered

due to the rough skin texture of the piglets. Evidently, effectiveness of the development

methods was strongly affected by the skin texture. Porous and textured surfaces cause more

difficulties for latent print deposition than smooth and non-porous surfaces and therefore

the possibility of this factor affecting the final appearance of the developed prints is not

excluded.

According to the scoring in Table 3a and 3b, the temperature and relative humidity did not

seem to have any effect on the quality of the developed prints. In fingerprints treated with

both powders, more prints stored in 37°C scored a grade 3 than fingerprints stored in 4°C and

24°C, which contradicts the finding of Shin and Argue where it was reported that bodies kept

at 4°C have a higher success rate compared to bodies with higher temperature where the oily

substances are maintained at a dispersive liquid state17. In addition, the results obtained also

69

contradicts the report that skin temperature of dead bodies that is 32°C or higher kept the

fingerprint residues in a liquid state that will risk the wash away of fingerprints5,24,25.

However, the results obtained did not have a specific and fixed pattern and this could be due

to a number of other reasons that includes the concentration of fingerprints, deposition

pressure, skin condition and body parts. The inconsistencies in the results could primarily be

due to the concentration of sebaceous secretions in the fingerprints. There were instances

where the quality of the fingerprints improved as the prints got more diluted and there were

also prints where the quality deteriorated as it got more diluted. This indicated that some

prints were too oily in the beginning and as it got more diluted, the ridge details became more

obvious; while some prints were less oily during the initial deposition hence the ridge details

faded as it got more diluted. Excessively oily fingerprints resulted in dark outline and

fingerprints with insufficient sebaceous secretions showed up as light and faint impressions.

Additionally, unevenly distributed secretions on the fingertips might have caused the

development of ridges in different parts of prints.

Besides that, some of the developed prints had ridge details that was only clear on the outer

edges (Figure 1) which could possibly be caused by deposition pressure, the location of

fingerprints on the body or a combination of both. When it comes to deposition of latent

fingerprints on skin, it is difficult to determine the optimum deposition pressure as the

sturdiness depends on the area of the body the skin is on. Fingerprint impressions tend to

look better when they are deposited on bony rather than fleshy parts of the body5. Deposition

pressure varies depending on the area of the body; bony parts require lesser pressure than

fleshy parts. To ensure that the entire fingerprints were fully transferred onto the side and

70

belly areas of the piglets where there is no bone to provide support, the deposition pressure

exerted was higher as the skin tend to sink in and moved around when fingertips were pressed

down. As a result, most of the fingerprints developed on these areas appeared smudged and

blurred. On the other hand, fingerprints deposited along the shoulder, back and loin areas of

the piglets where there were bones underneath the skin appeared better.

Figure 3. Fingerprints treated with black magnetic and Swedish black powders.

3.1.3 Cyanoacrylate Fuming + Powdering on Skin

Table 4a: Summary of results for CA fumed prints treated with black magnetic powder.

Black Magnetic Powder Temperature

(°C) Trial

Total Sample Number

Number of Fingerprints Graded 0 1 2 3 4

4 a

18 3 6 0 0 0

b 0 9 0 0 0

24 a

18 0 9 0 0 0

b 0 7 1 1 0

37 a

18 0 5 4 0 0

b 0 9 0 0 0

71

Table 4b: Summary of results for CA fumed prints treated with Swedish black powder.

Swedish Black Powder Temperature

(°C) Trial

Total Sample Number

Number of Fingerprints Graded 0 1 2 3 4

4 a

18 0 8 1 0 0

b 0 9 0 0 0

24 a

18 5 4 0 0 0

b 2 7 0 0 0

37 a

18 0 1 7 1 0

b 0 9 0 0 0

Based on the results in Table 7, the combination of CA fuming and powdering appeared to be

a less effective technique as compared to the use of dactyloscopic powders. Among the 108

CA fumed prints powdered with both black magnetic and Swedish black powders, only 1.8%

of the prints were graded 3 while 86% of the prints were graded either 1 or 0. Among the two

powders, CA fuming followed by black magnetic powder produced better results for prints

stored at 24°C. While with CA fuming and Swedish black powder, the quality of prints at 4°C

and 37°C were slightly better than those treated with magnetic powder. Fingerprints stored

at 37°C had the best results with both fingerprint powders. The temperature kept the prints

at a dispersive liquid state while retaining the moisture17, allowing the CA fumes and powders

to adhere more easily.

Just like any other recovery techniques, effectiveness of powdering after CA fuming is also

dependent on the quality of the fingerprints and additionally, CA development. Fingerprint

quality is affected by the concentration of sebaceous secretions on the fingertips and

deposition pressure. Although the differences in print quality was controlled by using one

individual’s secretions and prints, the concentration of the author’s sebaceous secretion

could still vary throughout the day. This might have been what caused both black magnetic

72

and Swedish black powders to produced fingerprints that varied in darkness and clarity. Both

powders produced dark prints that appeared smudged and either without any ridge detail or

with ridges visible only on the outer edges, hence, most prints were graded 1 (Table 4a and

4b). But as the prints became more diluted, the fingerprint impressions that had ridge details

on the edges eventually had more details showing up in other parts of the prints. It is evident

that the excessive oil residues in the fingerprints caused the prints to turn out dark and blurry.

Deposition pressure exerted might have contributed to producing the smudged and blurred

prints as well. On fingerprints that were less oily, the CA fumes and powders managed to

adhere to the little moisture there was and produced some very faint fingerprint impressions

with light ridge details. These fingerprint impressions eventually faded completely as the

prints became more diluted. It is worth noting that dark and smudged, and faint fingerprint

impressions is a constant occurrence in prints stored in all three temperatures.

In Table 4b, several prints stored in 24°C were scored 0 because the powders did not adhere

to the developed prints very well. This could be caused by deposited prints not being oily

enough prior to CA fuming, dryness of the prints post CA fuming, over fuming of the prints or

the thickness of the ridges post CA development. Powders tend to not stick to drier prints due

to the lack of moisture. In addition, over fuming can lead to CA fumes filling in the ridges of

latent fingerprints, making powdering useless. CA development could also produce ridges of

different thickness. CA fumed prints that have thinner ridges, are unhardened, on soft

surfaces like skin, or a combination of all can make the prints vulnerable to the movement of

fingerprint brushes and magnetic powder. The fumed prints could have been rubbed away

completely in the dusting process, causing the negative outcome.

73

3.2 Effectiveness of Lifters

3.2.1 Gel Lifters

Table 5. Summarised results for treated prints lifted with transparent gel lifters.

Temperature (°C)

Recovery Methods

Powders Number of Lifters Graded

0 1 2 3 4

4

Powdering Black magnetic 0 6 0 0 0

Swedish black 1 5 0 0 0

CA fuming + Powdering

Black magnetic 3 3 0 0 0 Swedish black 5 1 0 0 0

24

Powdering Black magnetic 1 5 0 0 0 Swedish black 0 6 0 0 0

CA fuming + Powdering

Black magnetic 5 1 0 0 0

Swedish black 3 3 0 0 0

37

Powdering Black magnetic 0 5 1 0 0

Swedish black 1 3 1 1 0

CA fuming + Powdering

Black magnetic 5 1 0 0 0

Swedish black 1 3 2 0 0

Transparet gel lifters were the least effective of all, only 7% of the prints lifted were graded 2

and above (Table 6). It worked fine when the developed prints were of excellent quality with

minimal background powdering and were on smooth and sturdy skin where the lifters can be

held properly. Even so, it was still difficult to lift prints completely without causing any

damage. The more commonly seen occurrences were incomplete lifting, inability to lift lighter

prints, and lifted prints appearing smudged and blurry. Gel lifters did not work well on uneven

surfaces i.e. above the ribs because it was unable to reach fingerprints deposited in the

grooves in between the ribs. Hence, more pressure was exerted in attempt to lift ridges in the

grooves but that caused the prints to smudge, damaging a decent fingerprint impression.

Additionally, recovery rate was also low when used on soft surfaces like the belly as the skin

tend to sink in when pressure was exerted, causing the lifters to slip, and smudging the prints.

Besides that, gel lifters were not effective when it comes to lifting prints with faint ridges. The

lifted ridges appeared even lighter and appeared blurry as well. Finally, the plastic backing

74

that covers the lifted prints were difficult to put back on and extra precaution had to be taken

to avoid damaging the lifted prints.

3.2.2 Instant Lifters

Table 6. Summarised results for treated prints lifted with instant white.

Temperature (°C)

Recovery Methods

Powders Number of Lifters Graded

0 1 2 3 4

4

Powdering Black magnetic 0 4 2 0 0 Swedish black 0 3 2 1 0

CA fuming + Powdering

Black magnetic 3 3 0 0 0

Swedish black 0 6 0 0 0

24

Powdering Black magnetic 0 4 1 1 0

Swedish black 0 5 1 0 0

CA fuming + Powdering

Black magnetic 1 5 0 0 0

Swedish black 5 1 0 0 0

37 Powdering

Black magnetic 0 5 1 0 0

Swedish black 0 6 0 0 0

CA fuming + Powdering

Black magnetic 1 5 0 0 0 Swedish black 3 3 0 0 0

Although no major difference, instant white lifters still worked better than gel lifters.

According to Table 7, 12.5% of the total lifted prints were graded 2 and above. More

importantly, instant lifters were easier to use. Ridges lifted were clear and accurate to the

developed prints on pig skin as long as the lifters were held properly. In some cases, lifted

prints were clearer than prior to being lifted. The instant lifters purchased came with a white

backing that protects the lifted prints and this white backing increased the contrast of the

developed prints, making it clearer than before. This lifter was not only useful on faint prints

but also on over powdered prints by lifting the prints twice. The first lift managed to remove

excess powder and the second lift lifted the ridge details that were under the excess powder.

However, this could risk breaking the powdered prints apart. Besides the advantages, instant

lifters just like gel lifters were not able to pick up ridges that were in grooves or on soft skin.

75

Furthermore, the recovery rate of thin and light ridges on textured skin was very low as the

lifters tend to lift more of the skin texture.

3.2.4 Silmark White

Table 7. Summarised results for treated prints lifted with Silmark white.

Temperature (°C)

Recovery Methods

Powders Number of Lifters Graded

0 1 2 3 4

4

Powdering Black magnetic 0 1 5 0 0 Swedish black 0 3 3 0 0

CA fuming + Powdering

Black magnetic 1 5 0 0 0

Swedish black 0 6 0 0 0

24

Powdering Black magnetic 0 4 2 0 0

Swedish black 0 4 2 0 0

CA fuming + Powdering

Black magnetic 0 5 0 1 0

Swedish black 2 4 0 0 0

37 Powdering

Black magnetic 0 1 3 2 0

Swedish black 0 5 1 0 0

CA fuming + Powdering

Black magnetic 0 4 2 0 0 Swedish black 0 3 2 1 0

Silmark white appeared to be the most effective among all the lifters. As compared to the 7%

and 12.5% from gel and instant lifters respectively, Silmark white had 33.3% of lifted prints

graded 2 and above (Table 8). It was able to lift developed fingerprints completely while

maintaining clear and sharp ridges. In some cases, lifted ridges appeared clearer than before

being lifted which conforms with Farber et al.’s statement that lifting the prints with silicone

lifter improved the results5. It could be caused by the contrast between the dark fingerprint

powders and light silicone lifters. There were also cases where ridges that were not visible on

skin became visible after being lifted. The most useful feature of the silicone lifter was that it

was capable of picking up fingerprint developed on uneven or soft skin as the lifter is in liquid

form during application. However, the silicone lifter is not without its cons. Fingerprint

impressions lifted off highly textured skin turned out to be a little blurry as the background

76

was often lifted as well. In addition, it failed to lift faint and blurry ridges because the faint

ridges were overpowered by skin texture. When fingerprints were over powdered, the prints

lifted did not have any ridge details because the ridges were obscured by the powders. It was

also noticed that after storing the silicone lifters for about a month in plastic containers, the

silicone had shrunken. This observation agreed with Baran’s statement that silicone lifter

shrinks as it dried or over time6. Thus, it is extremely important to preserve latent print

impressions by taking photographs. Lastly, if insufficient hardener was mixed, silicone lifters

can take quite some time to dry and are therefore a little more time consuming than the

instant and gel lifters.

4.0 Limitations and Future Studies

A limitation in studies involving deposition of latent fingerprints is the consistency and quality

of the generated fingerprints. A further study with a bigger sample size should be undertaken

to address this. Time constraint was also a limitation in this study. The samples were only

stored at their respective temperatures for 2 hours before being treated. There may be a

more significant difference in the results if they were stored longer periods. Further research

investigating the relationship between time, temperature and the effectiveness of latent

prints recovery techniques will be beneficial. Also, examining other glossy materials like

acetate sheets, thermal papers etc as potential direct transfer medium can also be beneficial

to forensic investigators in discovering cheaper, simpler and more convenient methods to

retrieve latent prints without putting human skin at risk by subjecting it to dactyloscopic

powders and chemicals. It is also important to conduct studies that compare the quality of

CA fumed prints to the quality of powdered CA fumed prints in order to clearly assess the

effectiveness of cyanoacrylate fuming on skin. Finally, future research on touch DNA recovery

77

from aged fingerprints exposed to extreme environmental conditions could be highly

advantageous as DNA is often deposited alongside with latent fingerprints. Further study on

the influence transparent gel lifters, instant white lifters and Silmark white have on the

recovery of DNA should be conducted.

5.0 Conclusion

Two of the three development methods (powdering and CA fuming with powdering) were

capable of enhancing latent fingerprints on pig skin stored at different temperatures.

Powdering was determined to be the most effective, followed by CA fuming and powdering,

and finally, direct transfer was the least effective method, yielding negative results with no

development at all. Fingerprint powders yielded 33% prints that were graded 2 and above as

compared to the 1.8% obtained from CA fuming and powdering. Among the 33%, 21% were

developed by black magnetic powder. Therefore, proving that black magnetic powder was

the better adhesive agent; but Swedish black powder produced more prints that were scored

2 and above when used on CA fumed prints. Direct transfer on the other hand had 0% prints

graded 2 and above.

Importantly, temperature had a slight effect on the effectiveness of the development

techniques. Fingerprints stored at 4°C were probably solidified, making them difficult to be

lifted by the direct transfer medium hence the negative results. In powdered CA fumed prints,

best results were seen in prints stored at 37°C because the moisture in the prints was

maintained at that temperature, making it easier for the CA fumes and powders to adhere to.

However, the results were inconsistent and there was no specific trend to it.

78

Finally, all three lifters were capable of lifting fingerprints developed by powdering and CA

fuming but they differed in terms of effectiveness. The most useful and easy to use lifter was

the Silmark white, with 33.3% of the prints graded 2 and above. Silicone lifters are useful on

soft and uneven surfaces due to its liquid form upon application, it does not require pressure

exertion and it allows the lifters to get into the grooves of uneven substrates. On the contrary,

there was not much difference between the results obtained from instant lifters and gel

lifters, 78with 12.5% and 7% prints graded 2 or above, respectively. However, instant lifters

were easier to use than gel lifters because they were easier to control and hold properly to

prevent slippage that can lead to smudging the prints.

This study shows that temperature did not have much effect on the effectiveness of the

development techniques. The most effective method was powdering directly on skin and

magnetic powder was the better adherent. Nonetheless, the recovery of latent fingerprint on

skin is still strongly affected by a number of other factors like quality of fingerprints,

concentration of fingerprints residue, skin conditions, pressure, location of fingerprints etc.

Lastly, it was also determined that silicone lifter specifically Silmark white was the most

efficacious lifter among all.

6.0 References

79

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2001; 2:123. doi: 10.4172/2155-6180.1000123.

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[Internet]. 2019 [cited 2020 Oct 8]; vol(7). Available from:

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Skin-A-Silent-Diagnosis.pdf.

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vol(47): 136-140. doi: https://doi.org/10.1016/j.scijus.2007.01.002.

4. Farber D, Seul A, Weisser JH, Bohnert M. Recovery of latent fingerprints and DNA on

human skin. J Forensic Sci. 2010; vol(55): 1457-1461. doi: 10.1111/j.1556-

4029.2010.01476.x

5. Baran M. Lifting fingerprints from skin using silicone. Can Soc Forensic Sci J. 2009;

vol(42):121-131. doi: 10.1080/00085030.2009.10757601.

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https://susanabooher.files.wordpress.com/2016/10/latent-fingerprints-2.pdf.

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vol(9):1192-1198. doi: 10.17577/IJERTV9IS060868.

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from human skin surface. J Forensic Sci [e-journal]. 1978 [cited 3 Dec 2020]; vol(23):135-

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16. Sampson WC, Sampson KL. A direct transfer technique using copy paper. CBDIAI

[Internet]. Chesapeake Bay Division IAI. 2004 [cited 2021 Jan 15]. Available from:

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ng_copy_paper.pdf.

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18. Johnston A, Rogers K. The effect of moderate temperatures on latent fingerprint

chemistry. Appl Spectrosc. 2017; vol(71): 2102-2110. doi:

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19. Osilla EV, Marsidi JL, Sharma Sandeep. Physiology, temperature regulation. StatPearls

Publishing [e-book]. 2017 [cited 2020 Nov 7]. Available from:

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20. Bandey HL, Gibson AP. Fingerprint Development and Imaging Newsletter: Special Edition.

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21. Miller P. Choosing the Best Fingerprint Powder for Your Scene. Evidence Technology

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22. Hebrard J, Donche A. Fingerprint Detection Methods on Skin: Experimental Study on 16

Live Subjects and 23 Cadavers. J Forensic Identif [e-journal]. 1994 [cited 2020 Dec 3];

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dine_and_a-naphthoflavone.

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7.0 Appendices:

Appendix 1. Grades given for the latent prints treated with different methods

(a) Direct transfer – Black Magnetic Powder

37oC

Trial a Trial b Dilution 1 2 3 1 2 3

1st set 0 0 1 0 0 0

24oC

Trial a Trial b Dilution 1 2 3 1 2 3

1st set 1 1 0 0 0 0

4oC

Trial a Trial b Dilution 1 2 3 1 2 3

1st set 0 0 0 0 0 0

(b) Direct Transfer – Swedish Black Powder

37oC Trial a Trial b

Dilution 1 2 3 1 2 3

1st set 0 0 0 0 0 0

24oC Trial a Trial b

Dilution 1 2 3 1 2 3

1st set 1 0 0 0 0 0

4oC Trial a Trial b

Dilution 1 2 3 1 2 3

1st set 0 0 0 0 0 0

83

(c) Powdering - Black Magnetic Powder

37oC

Trial a Trial b

Dilution 1 2 3 1 2 3

1st set 2 3 3 3 2 2 Silmark 1 2 3 2 3 2

2nd set 2 1 1 1 0 1 Instant Lifter 2 1 1 1 1 1

3rd set 3 1 1 1 2 1 Gel Lifter 2 1 1 1 1 1

24oC Trial a Trial b

Dilution 1 2 3 1 2 3

1st set 1 1 2 1 2 2 Silmark 1 1 2 1 1 2

2nd set 1 1 1 2 2 3 Instant lifter 1 1 1 1 2 3

3rd set 1 1 1 1 1 2 Gel lifter 0 1 1 1 1 1

4oC Trial a Trial b

Dilution 1 2 3 1 2 3 1st set 2 2 1 2 2 2

Silmark 2 2 1 2 2 2 2nd set 1 1 1 1 1 1

Instant lifter 1 1 1 1 2 2

3rd set 1 1 1 2 2 1 Gel lifter 1 1 1 1 1 1

(d) Powdering - Swedish Black Powder

37oC

Trial a Trial b

Dilution 1 2 3 1 2 3

1st set 1 1 1 2 1 2 Silmark 1 1 1 1 1 2 2nd set 1 1 1 1 1 1

Instant lifter 1 1 1 1 1 1 3rd set 3 3 3 1 1 1

Gel lifter 2 3 1 1 1 0

84

24oC Trial a Trial b

Dilution 1 2 3 1 2 3

1st set 1 1 2 1 1 1 Silmark 1 2 2 1 1 1 2nd set 1 1 1 1 1 1

Instant lifter 1 1 2 1 1 1 3rd set 1 1 1 1 1 1

Gel lifter 1 1 1 1 1 1

4oC Trial a Trial b

Dilution 1 2 3 1 2 3 1st set 1 1 1 1 1 2

Silmark 1 1 1 2 2 2 2nd set 1 1 2 2 2 3

Instant lifter 1 1 1 2 2 3 3rd set 1 1 1 1 2 2

Gel lifter 1 1 1 1 0 1

(e) CA Fuming – Black Magnetic Powder

37oC

Trial a Trial b Dilution 1 2 3 1 2 3

1st set 1 2 2 1 1 1 Silmark 3 3 2 1 1 1 2nd set 2 1 1 1 1 1

Instant lifter 1 1 0 1 1 1 3rd set 2 1 1 1 1 1

Gel lifter 1 0 0 0 0 0

24oC

Trial a Trial b Dilution 1 2 3 1 2 3

1st set 1 1 1 1 3 1 Silmark 1 1 1 1 3 1 2nd set 1 1 1 1 1 2

Instant lifter 0 1 1 1 1 1 3rd set 1 1 1 1 1 1

Gel lifter 0 0 0 1 1 1

85

4oC Trial a Trial b

Dilution 1 2 3 1 2 3

1st set 1 1 0 1 1 1 Silmark 1 0 0 1 1 1 2nd set 1 1 0 1 1 1

Instant lifter 1 1 0 0 0 1 3rd set 1 1 0 1 1 1

Gel lifter 1 1 0 0 0 1

(f) CA Fuming – Swedish Black Powder

37oC

Trial a Trial b

Dilution 1 2 3 1 2 3 1st set 3 2 2 1 1 1

Silmark 3 2 2 1 1 1 2nd set 1 2 2 1 1 1

Instant lifter 1 2 1 1 0 0 3rd set 2 2 2 1 1 1

Gel lifter 1 2 2 1 1 0

24oC

Trial a Trial b Dilution 1 2 3 1 2 3

1st set 1 1 0 1 1 0 Silmark 1 1 0 1 1 0 2nd set 0 0 0 1 1 1

Instant lifter 0 0 0 1 0 0 3rd set 1 1 0 1 0 1

Gel lifter 1 1 0 1 0 0

4oC

Trial a Trial b Dilution 1 2 3 1 2 3

1st set 1 1 1 1 1 1 Silmark 1 1 1 1 1 1 2nd set 1 1 1 1 1 1

Instant lifter 1 1 1 1 1 1 3rd set 1 2 1 1 1 1

Gel lifter 0 0 0 1 0 0