Unit 5- Fingerprints and Other Prints (palm, lip, shoe, tire)

Transcription

1 Unit 5- Fingerprints and Other Prints (palm, lip, shoe, tire)

2 Historical Perspective: Quest for reliable method of personal identification: Tattooing Numbers Branding Cutting off Fingers Holocaust Survivor

3 Pre Fingerprints: Bertillon Measurements Alphonse Bertillon, French police expert (1883) Used a series of precise body measurements (aka anthropometry) For 20 years this was considered the most accurate method of identification.

4 Bertillon Cards were made for each prisoner consisting of a: Body height Outstretched reach of both arms Trunk height Width of the head Length of the head Length of the right ear Width of the right ear Length of the left foot Length of the left middle finger Length of the left little finger Length of the left forearm & a Fingerprint See any problems with this method?

5 Downfall of Bertillon Will and William West Cases 1903, Will West arrived at Ft. Leavenworth Prison, Kansas Prison files showed a William West already in the prison Looks and measurements nearly identical to the new prisoner Needed better way of identifying prisoners Fingerprints! Will West Bertillon Measurements 178.5; 187.0; 91.2; 19.7; 15.8; 14.8; 6.6; 28.2; 12.3; 9. William West Bertillon Measurements 177.5; 188.0; 91.3; 19.8; 15.9; 14.8; 6.5; 27.5; 12.2; 9.6

6 3 Founding Principles of Fingerprints Fingerprints are: 1. Unique (even identical twins have unique prints) FBI has 50 million fingerprints in its computer system & no matches. 2. Permanent Form 8 th week of development Only get larger as you grow Really difficult to remove fingerprints 3. Can be classified Arch, whorl, loops, etc

7 Anatomy of Fingerprints (aka friction ridges ) Close-up of the friction ridges and pores. Purpose: for gripping objects On palms and soles of feet Sweat Pores - release perspiration (water, oils, fats, and proteins). Removal of prints requires taking off entire epidermis (see John Dillinger slide)

8 John Dillinger tried to remove Tried to have his prints cut and burned with acid fingerprints More info on fingerprint removal

9 Fingerprint Classification

10 3 Basic Classifications

11 1 or more ridges entering and exiting from the same side. Loop (1 Delta) Types: Right slant Left slant Most common: % frequency in population

12 Types: Plain Central Pocket Double Loop Accidental Whorl (2 Deltas, 1 Core) % frequency in population

13 Arch Ridges enter on one side and cross to the other side while rising upward in the middle. Types: Plain Tented **Often confused with loops by inexperienced observers. Least common: 0-5 % frequency in population

14 Sub Classification of the 3 main fingerprint patterns

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16 Ridge Characteristics (aka minutiae) allow for individualization of prints Most adults have 150 identification marks on each finger

17 Ridge Characteristics Ridge ending Short ridge Dot or fragment Bifurcation Double bifurcation Trifurcation Bridge Island Enclosure Spur Minutiae characteristics of ridge patterns

18 Can you identify the minutiae in this fingerprint?

19 Automated Fingerprint Identification How it works: Computer scans and digitally encodes fingerprints Records the position and orientation of minutiae (ridge ending/ bifurcations/ etc.) Creates a geometric pattern Stores in a data base & allows 1000 s of fingerprints to be compared per second via computer System (AFIS)

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21 Comparison of unknown prints in AFIS AFIS ranks known prints from files to unknown print An expert compares to determine if there s a match. Criminal courts consider 12 points a match for prints. Known print on file Unknown print

22 Live Scan Allows for agencies to scan prints directly into a computer data base. Allows for fingerprints to be checked against AFIS system in minutes. No more ink and paper

23 Developing Latent Prints

24 Latent Printsnot visible to the naked eye Come from natural secretions from glands in human skin Developed for them to become visible. Dusting for latent prints

25 Developing Latent Prints w/ Powders (magnetic/ regular) adhere to water & fatty deposits. Best on hard surfaces (anything a drop of water would roll off of). Dusting Powders Ex: glass, mirrors, tile, painted wood, plastic, magazine covers, metal, rubber

26 Developing Latent Prints- Ninhydrin (spray) reacts with amino acids to produce a purple color. best on porous substances: ex: paper, wood, cardboard Ninhydrin Fingerprint

27 Cyanoacrylate super glue fumes react fingerprint chemicals to form a hard, whitish deposit. Best on hard surfaces (anything a drop of water would roll off of) Ex: glass, mirrors, tile, painted wood, plastic, magazine covers, metal, rubber

28 Super Glue Fuming Reacts with moisture from latent residue Heat speeds reaction Bonds latent deposit to surface Need adequate ventilation (Note* - Eyelashes bond very well!)

29 Other methods: Iodine Fingerprint

30 Leucocrystal Violet On Carpet

31 Amido Black

32 Titanium Dioxide Blood Prints On Dark Surfaces

33 Preserving Fingerprints Super Glue at scene helps preserve print for transporting (on hard objects) Photograph at scene Bring object back with you if small enough Lift the prints if there are large objects (cars/ doors)

34 Other Prints Palm friction ridges can be identified and may be used against suspects.

35 Footprints are taken at birth as a means of identification of infants. Other Prints

36 Other Prints Lips display several common patterns Short vertical lines Short horizontal lines Crosshatching Branching grooves

37 Other Prints- Teeth bite marks are unique and can be used to identify suspects. imprints in gum

38 Use of some type of body metrics for the purpose of identification. Biometrics Ex: retinal or iris patterns, voice recognition, hand geometry used to control entry or access to computers or other structures; can identify a person for security purposes;

39 More about Prints For additional information about prints and crime, check out Court TV s Crime Library /fingerprints/1.html