Methods of Identification

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

Fingerprinting

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

What is a fingerprint?

Layers of the Skin Epidermis Epidermis Dermis Dermis Hypodermis Hypodermis

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

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

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

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

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

General classifications Loops Loops –60-70% of the population Whorls Whorls –25-35% Arches Arches –5%

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. There is one delta. The number of ridge lines forming the loop is an identifying characteristic too The number of ridge lines forming the loop is an identifying characteristic too

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

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

Whorls 2 or more deltas 2 or more deltas

Types of Whorls Plain whorl Plain whorl Consists of one or more ridges which make or tend to make a complete circuit, with 2 deltas 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. 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 At least one type line forms a circle

Central pocket whorl Central pocket whorl Consists of one or a few ridges which make or tend to make a complete circuit, with 2 deltas 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. 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 At least one type line forms a circle

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

Accidental whorl Accidental whorl Contains 3 or more deltas Contains 3 or more deltas

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

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

Types of arches Tented arch Tented arch Contains a significant upthrust Contains a significant upthrust

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

Fingerprint ID Practice Assume prints are from the left hand Assume prints are from the left hand

A B C A B C D E F D E F

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

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

Types of minutiae Ridge ending Ridge ending Bifurcation/ Trifurcation Bifurcation/ Trifurcation

Dot Dot Island Island –Ridge line Lake Lake –Enclosure

Crossover Crossover Bridge Bridge Ellipse Ellipse

Spur Spur

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

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

Types of prints found in the environment Latent 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 Visible –Prints contaminated with blood, ink, etc. that leave visible prints Plastic (molded) Plastic (molded) –Impression left in a soft substance (i.e. soap, wax)

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

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

3. Iodine fuming 3. Iodine fuming Good for paper Good for paper

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

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

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

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

Example Whorls ID’d in right index and left index fingers Whorls ID’d in right index and left index fingers Arches or loops everywhere else Arches or loops everywhere else What is the Primary Classification value? 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

Example R. Index + R. Ring + L. Thumb + L. Middle + L. Little + 1 R. Thumb + R. Middle + R. Little + L. Index + L. Ring = = = 3

AFIS – Automated fingerprint identification system

Computer scanners identify ridge endings and bifurcations only, and their relative positions are mapped 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 Prints lifted at the crime scene are compared to fingerprints on file A group of suspect fingerprint cards is identified A group of suspect fingerprint cards is identified An examiner does a point by point comparison 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 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 Computer enhancement can also compensate for imperfections in lifted latent prints