Science of FingerprintsScience of Fingerprints

What is a Fingerprint?What is a Fingerprint?Based on the key premise….Based on the key premise….

Doctor Locard, a French scientist active in the 1920’s, Doctor Locard, a French scientist active in the 1920’s, propounded the law of physics that applies to the propounded the law of physics that applies to the depositing of latent fingerprint impressions:depositing of latent fingerprint impressions:

WWhen two objects come into contact there is hen two objects come into contact there is always a transfer of material from each object always a transfer of material from each object to the other. Often this transfer is obvious, at to the other. Often this transfer is obvious, at least in one direction, but even when the least in one direction, but even when the amount of material transferred, or its nature amount of material transferred, or its nature is such that nothing is visible, there is always is such that nothing is visible, there is always some transfer.” (Locard, The Criminal some transfer.” (Locard, The Criminal Investigation and Scientific Methods, 1920)Investigation and Scientific Methods, 1920) . .

What is a Fingerprint?What is a Fingerprint?

• An impression of the friction ridge skin An impression of the friction ridge skin located on the fingers, thumbs, palms, located on the fingers, thumbs, palms, soles of the feet and toes of a person. soles of the feet and toes of a person.

• There is no biological difference There is no biological difference between these surfaces concerning between these surfaces concerning the comparison and identification of the comparison and identification of friction ridge skin detail.friction ridge skin detail.

What are LATENT What are LATENT Fingerprints?Fingerprints?

– Latent means hidden or not Latent means hidden or not visible.visible.

– In modern Police usage, the In modern Police usage, the term Latent refers to all term Latent refers to all CHANCE CHANCE or or UNINTENTIONAL UNINTENTIONAL impressions that are of impressions that are of evidentiary value.evidentiary value.

What are LATENT What are LATENT Fingerprints?Fingerprints?

• Those impressions are from friction Those impressions are from friction ridge skin deposited onto a surface ridge skin deposited onto a surface upon contact.upon contact.

• A A truetrue latent fingerprint is latent fingerprint is composed of the perspiration, oils & composed of the perspiration, oils & waxes exuded from the body and waxes exuded from the body and may require development such as may require development such as powders to be seen.powders to be seen.

LATENT FINGERPRINTS LATENT FINGERPRINTS FOUR MAIN TYPESFOUR MAIN TYPES..

• VISIBLE - VISIBLE - i.e. in paint, blood, ink or other visible i.e. in paint, blood, ink or other visible medium.medium.

• INVISIBLE - INVISIBLE - i.e. Latent fingerprints made by i.e. Latent fingerprints made by perspiration & other substances on the surface of the perspiration & other substances on the surface of the skin which may require some form of development.skin which may require some form of development.

• MOULDED - MOULDED - also known as Plastic Fingerprints. e.g. also known as Plastic Fingerprints. e.g. moulds of impressions in substances such as grease, moulds of impressions in substances such as grease, butter, wax or putty.butter, wax or putty.

• ETCHED -ETCHED - impressions eroded into metals by the impressions eroded into metals by the corrosive compounds of the skin surface matter. corrosive compounds of the skin surface matter.

3 Principles must apply for a 3 Principles must apply for a latent fingerprint impression to latent fingerprint impression to be found.be found.

• Sufficient matter must be Sufficient matter must be transferred on contact.transferred on contact.

• The duration of the components of The duration of the components of latent matter can vary, but the life latent matter can vary, but the life is usually limited.is usually limited.

• The contact surface must be such The contact surface must be such that it does not destroy or that it does not destroy or dissipate the transferred material.dissipate the transferred material.

As a general guideAs a general guide

• The process of leaving identifiable The process of leaving identifiable fingerprints at a crime scene is one of fingerprints at a crime scene is one of pure chance. A firm contact between pure chance. A firm contact between 2 to 7kgs of pressure from the friction 2 to 7kgs of pressure from the friction ridge skin onto the contact surface is ridge skin onto the contact surface is best, but logic tells us that this best, but logic tells us that this cannot be achieved all the time and cannot be achieved all the time and there are other factors that can affect there are other factors that can affect the life of the latent impressions too. the life of the latent impressions too.

Factors affecting the Factors affecting the durability of latent durability of latent impressionsimpressions • CComposition of the latent impressionomposition of the latent impression

• AAmount of matter depositedmount of matter deposited

• RReceiving surface physical properties eceiving surface physical properties and condition and condition

• PPosition of the latent impressionosition of the latent impression

• EEnvironmental conditionsnvironmental conditions

• TTime elapsed since latent was ime elapsed since latent was depositeddeposited

What are suitable surfaces What are suitable surfaces for Fingerprints?for Fingerprints?

• Objects which the offender/s may have Objects which the offender/s may have picked up or moved. picked up or moved.

• Objects which the offender/s may have left Objects which the offender/s may have left behind at the scene. behind at the scene.

• Shiny non porous surfaces.Shiny non porous surfaces.

• Items like t.v.’s & computers which have a Items like t.v.’s & computers which have a rough exterior, may have a shiny base.rough exterior, may have a shiny base.

Three types of patterns Three types of patterns that most commonly occur that most commonly occur are:are:

Arch PatternArch Pattern

AA pattern type in which the ridges flow pattern type in which the ridges flow from left to right with a slight rise or from left to right with a slight rise or hill in the centre of the patternhill in the centre of the pattern

Loop Pattern Loop Pattern

AA pattern type in which one or pattern type in which one or more of the ridges enter on either more of the ridges enter on either side of the impression, recurve and side of the impression, recurve and terminate, or tend to terminate on terminate, or tend to terminate on or toward the same side of the or toward the same side of the impression from where the ridge or impression from where the ridge or ridges entered. ridges entered.

Whorl PatternWhorl Pattern

AA pattern having at least two deltas pattern having at least two deltas with a complete recurve in front of with a complete recurve in front of each. A whorl has two deltas and at each. A whorl has two deltas and at least one ridge making a complete least one ridge making a complete circuit which iscircuit which is spiral, oval or circular spiral, oval or circular in shape.in shape.

STATE FINGERPRINT BUREAUXSTATE FINGERPRINT BUREAUX

1903 - Victoria (Sharp)1903 - Victoria (Sharp)

1904 - South Australia (Lingwoodsmith)1904 - South Australia (Lingwoodsmith)

1904 - Queensland (Fowler)1904 - Queensland (Fowler)

1912 - Tasmania (Weston)1912 - Tasmania (Weston)

1928 - Western Australia (Penrose)1928 - Western Australia (Penrose)

1957 - Northern Territory (McDonald)1957 - Northern Territory (McDonald)

1967 - Canberra A.C.T. (Broomby)1967 - Canberra A.C.T. (Broomby)

History of Fingerprints in AustraliaHistory of Fingerprints in Australia

• 1902 The commencement of 1902 The commencement of fingerprint of prisoners in NSW Gaols.fingerprint of prisoners in NSW Gaols.

• 1903 The Police took delivery of 6000 1903 The Police took delivery of 6000 fingerprints from the Prisons Dept. fingerprints from the Prisons Dept. Sergeant Childs as the officer in Sergeant Childs as the officer in charge.charge.

• 1941 Fingerprint Section commenced 1941 Fingerprint Section commenced operation as the Central Fingerprint operation as the Central Fingerprint Bureau of Australia.Bureau of Australia.

New South Wales Fingerprint HistoryNew South Wales Fingerprint History

• 1985 Commenced conversion of all State 1985 Commenced conversion of all State Bureaus fingerprints to AFIS. 1986Bureaus fingerprints to AFIS. 1986Commenced the use of the computerCommenced the use of the computer system on a limited basis.system on a limited basis.

• 1987 Conversion completed, 1,366,727 sets 1987 Conversion completed, 1,366,727 sets of fingerprints converted into the computer of fingerprints converted into the computer data base.data base.

• 1987 Central Fingerprint Bureau of Australia 1987 Central Fingerprint Bureau of Australia reverted to the NSW Fingerprint Section.reverted to the NSW Fingerprint Section.

• September 2000 the introduction September 2000 the introduction of of Livescan technology at Burwood Livescan technology at Burwood Police Police StationStation

• April 2001 AFIS II. The installation April 2001 AFIS II. The installation of the of the Sagem Morpho systemSagem Morpho system

What is Livescan ?What is Livescan ?

•Livescan is an electronic workstationLivescan is an electronic workstation

•That uses digital imaging That uses digital imaging and laser technologyand laser technology •To capture finger and palm To capture finger and palm print dataprint data

Benefits of LivescanBenefits of Livescan

• Real-time identification of Persons in Real-time identification of Persons in custodycustody

• Quality control of fingerprint captureQuality control of fingerprint capture

• Improved fingerprint databaseImproved fingerprint database

• Clean, efficient capture processClean, efficient capture process

• Integration with other Forensic/Policing Integration with other Forensic/Policing information systems.information systems.

Livescan TechnologyLivescan Technology

Techniques For Fingerprint Techniques For Fingerprint Detection EnhancementDetection Enhancement

The latent fingermark is invisible and The latent fingermark is invisible and hence, for its exploitation, it must hence, for its exploitation, it must be given characteristics which be given characteristics which differentiate it from the surface on differentiate it from the surface on which it is found. which it is found. Freckelton & Freckelton & Selby (1995 p 6791)Selby (1995 p 6791)

Enhancement TechniquesEnhancement Techniques

• OPTICAL METHODS: Forensic Light OPTICAL METHODS: Forensic Light Sources (FLS) which are high Sources (FLS) which are high intensity light sources designed for intensity light sources designed for fingerprint detection. One example fingerprint detection. One example is the Pollilite. is the Pollilite.

Physical Techniques used for FP Physical Techniques used for FP

detectiondetection Fingerprint powders used at crime scenes:Fingerprint powders used at crime scenes:White White - composed of kaolin, talc and titanium - composed of kaolin, talc and titanium

dioxide. dioxide.

BlackBlack - a vegetable (carbon) based powder. - a vegetable (carbon) based powder.

Grey magneticGrey magnetic - fine iron filings mixed with - fine iron filings mixed with appropriate colour powder. appropriate colour powder.

Black magneticBlack magnetic - fine iron filings mixed with the - fine iron filings mixed with the appropriate coloured powder. appropriate coloured powder.

FluorescentFluorescent - can be used on multicoloured - can be used on multicoloured surfaces (e.g. coke cans, multicoloured glossy surfaces (e.g. coke cans, multicoloured glossy magazine covers) and are viewed using UV light magazine covers) and are viewed using UV light and filters.and filters.

Advanced Development TechniquesAdvanced Development Techniques

One very common method used is:One very common method used is:Cyanoacrylate (Superglue/loctite) fuming. Cyanoacrylate (Superglue/loctite) fuming. The liquid is heated under strict controlled The liquid is heated under strict controlled

conditions which forms a vapour that conditions which forms a vapour that reacts with sebaceous (fatty) and reacts with sebaceous (fatty) and eccrine (water soluble) components of a eccrine (water soluble) components of a fingerprint deposit forming a hard, fingerprint deposit forming a hard, white image. The technique is most white image. The technique is most suited to non-porous surfaces, e.g. suited to non-porous surfaces, e.g. glass, plastics and firearms.glass, plastics and firearms.

Latent impressions produced by Latent impressions produced by cyanoacrylate development can be cyanoacrylate development can be further enhanced by the use of a further enhanced by the use of a luminescent stain such asluminescent stain such as Rhodamine 6GRhodamine 6G or or ArdroxArdrox. After . After the application of the stain, the the application of the stain, the fingerprints are strongly fingerprints are strongly luminescent and can then be luminescent and can then be viewed during excitation with viewed during excitation with varying light sources.varying light sources.

Questions?Questions?