Methods of Identification

1. Methods of Identification

2. Presumptive vs. Positive ID • Personal viewing of victim • Fingerprints • Dental records • Radiographs and anthropology • DNA analysis • Facial/photo superimposition • Scars, marks, tattoos, etc. • Personal effects • Clothing, body artifacts • Environment

3. Fingerprinting

4. History • 1880- Dr. Henry Faulds • First used fingerprints at a crime scene to ID the perpetrator • 1892- Sir Francis Galton • Published first textbook “Fingerprints” • 1897- Sir Edward Henry • Proposed a classification system adopted by Scotland Yard • System still widely used • 1910- • Accepted by US as a method of identification • 1930- • FBI set up National fingerprint file

5. What is a fingerprint?

6. Layers of the Skin • Epidermis • Dermis • Hypodermis

7. Superficial, ~20% of dermis Dermal papillae form ridges on hands and feet to increase friction Dermis - Papillary layer

8. Deeper, thick layer Flexure lines – dermal infoldings at wrist, palms, knees, etc. to secure skin to deep tissue Eccrine sweat glands - primarily for thermoregulation Sebaceous glands - oil Dermis - Reticular layer

9. Develop in utero ~13-15 weeks of gestation • Ridges are unique and permanent • The patterns never changes except in size

10. Print left by secretions from pores in the ridges • 18 major components • Primarily water, amino acids + salts • Some oils

11. General features of all prints • Ridges / ridge lines – raised part of the skin, ~150 per finger • Furrows – lowered skin • Minutiae – small, unique ridge characteristics • Delta – point where 3 ridge lines meet in a triangle • Core – center of the fingerprint

12. General classifications • Loops • 60-70% of the population • Whorls • 25-35% • Arches • 5%

13. Loops One or more of the ridges enters on one side of the impression  recurves  touches or crosses the line running from the delta to the core  and terminates one the same side where the ridges entered • There is one delta. • The number of ridge lines forming the loop is an identifying characteristic too

14. Types of loops • Two bones in the lower arm • Radius - attaches to wrist/hand closest to the thumb • Ulna – attaches closest to little finger

15. Radial loop • Ridge lines enter/exit on the side of the finger pointing towards the thumb • Not common • Ulnar loop • Ridge lines enter/exit on the side of the finger pointing towards the little finger

16. Whorls • 2 or more deltas

17. Types of Whorls • Plain whorl • Consists of one or more ridges which make or tend to make a complete circuit, with 2 deltas • If an imaginary line is drawn between deltas, there is at least one recurving ridge within the inner pattern area that is cut or touched.  • At least one type line forms a circle

18. Central pocket whorl • Consists of one or a few ridges which make or tend to make a complete circuit, with 2 deltas • If an imaginary line is drawn NO recurving ridges within the inner pattern are cut or touched. • At least one type line forms a circle

19. Double loop whorl • Consists of two separate and distinct loop formations with two separate and distinct shoulders and two deltas.

20. Accidental whorl • Contains 3 or more deltas

21. Arches • Ridges run from one side to the other, making no backward turn. • Generally there is no delta + no significant core • If there is a delta recurving ridge must intervene between the core and delta points.

22. Types of arches • Plain arch • The overall pattern area tends to just flow through the print with no significant changes

23. Types of arches • Tented arch • Contains a significant upthrust

24. Composites • Include patterns in which combinations of the tented arch, loop and whorl are found in the same print

25. Fingerprint ID Practice • Assume prints are from the left hand

26. A B C D E F

27. Plain whorl Ulnar loop Tented arch Plain arch Central pocket whorl Double loop whorl

28. Minutiae • Unique identifying points • FBI requires 8 for a positive ID • Ranges from 5-12 in different states

29. Types of minutiae • Ridge ending • Bifurcation/ Trifurcation

30. Dot • Island • Ridge line • Lake • Enclosure

31. Crossover • Bridge • Ellipse

32. Spur

33. Fingerprint ID techniques • 1. Take a ten-print • ID general classification for each finger

34. Fingerprint ID techniques • 2. Balloon print of right index finger • ID general classification • ID as many different types of minutiae as possible

35. Types of prints found in the environment • Latent • Formed by oil + sweat deposited by a person’s fingers when they touch a surface • Invisible to the naked eye, must be developed • Visible • Prints contaminated with blood, ink, etc. that leave visible prints • Plastic (molded) • Impression left in a soft substance (i.e. soap, wax)

36. Latent print detection • 1. Dusting powders • Normal • Grey vs. black • Magnetic • Fluorescent • Good for hard or non-absorbent surfaces

37. 2. Cyanoacrylate fuming • Turns a latent print into a permanent visible print (arrested print) • Good for plastics + metals

38. 3. Iodine fuming • Good for paper

39. 4. Ninhydrin spray • Good for paper, reacts with amino acid residues in sweat

40. 5. Silver nitrate (physical developers) • Good for porous surfaces like currency, wood + cardboard, recognizes lipids

41. Methods of Comparison • Henry Primary Classification System • Calculate the value given the following equation: Pair # 1 2 3 4 5 R. Index + R. Ring + L. Thumb + L. Middle + L. Little + 1 R. Thumb + R. Middle + R. Little + L. Index + L. Ring + 1

42. Numerical value assigned to any WHORL in the numerator or denominator • Pair 1 = 16 • Pair 2 = 8 • Pair 3 = 4 • Pair 4 = 2 • Pair 5 = 1 • ARCHES and LOOPS = 0

43. Example • Whorls ID’d in right index and left index fingers • Arches or loops everywhere else • What is the Primary Classification value? Remember: R. Index + R. Ring + L. Thumb + L. Middle + L. Little + 1 R. Thumb + R. Middle + R. Little + L. Index + L. Ring + 1

44. Example R. Index + R. Ring + L. Thumb + L. Middle + L. Little + 1 R. Thumb + R. Middle + R. Little + L. Index + L. Ring + 1 16 + 0 + 0 + 0 + 0 + 1 = 17 0 + 0 + 0 + 2 + 0 + 1 = 3

45. AFIS – Automated fingerprint identification system

46. Computer scanners identify ridge endings and bifurcations only, and their relative positions are mapped • Prints lifted at the crime scene are compared to fingerprints on file • A group of suspect fingerprint cards is identified • An examiner does a point by point comparison • The computer can compare the suspect's print to 500,000 fingerprint cards in less than a second • Computer enhancement can also compensate for imperfections in lifted latent prints