Methods of Identification. Presumptive vs. Positive ID Personal viewing of victim Personal viewing...

Methods of Methods of IdentificationIdentification

Presumptive vs. Presumptive vs. Positive IDPositive ID

Personal viewing of victimPersonal viewing of victim FingerprintsFingerprints Dental recordsDental records Radiographs and Radiographs and

anthropologyanthropology DNA analysisDNA analysis Facial/photo superimpositionFacial/photo superimposition Scars, marks, tattoos, etc.Scars, marks, tattoos, etc. Personal effects Personal effects

– Clothing, body artifactsClothing, body artifacts Environment Environment

FingerprintinFingerprintingg

HistoryHistory

1880- Dr. Henry Faulds1880- Dr. Henry Faulds– First used fingerprints at a crime scene to ID the First used fingerprints at a crime scene to ID the

perpetratorperpetrator 1892- Sir Francis Galton1892- Sir Francis Galton

– Published first textbook Published first textbook “Fingerprints” “Fingerprints” 1897- Sir Edward Henry 1897- Sir Edward Henry

– Proposed a classification system adopted by Proposed a classification system adopted by Scotland YardScotland Yard

– System still widely usedSystem still widely used 1910-1910-

– Accepted by US as a method of identificationAccepted by US as a method of identification 1930-1930-

– FBI set up National fingerprint fileFBI set up National fingerprint file

What is a fingerprint?What is a fingerprint?

Layers of Layers of the Skinthe Skin

EpidermisEpidermis DermisDermis HypodermHypoderm

isis

Dermis - Papillary Dermis - Papillary layerlayer

Superficial, ~20% of Superficial, ~20% of dermisdermis

Dermal papillaeDermal papillae form ridges on form ridges on hands and feet to hands and feet to increase friction increase friction

Dermis - Reticular Dermis - Reticular layerlayer

Deeper, thick layerDeeper, thick layer Flexure linesFlexure lines – –

dermal infoldings at dermal infoldings at wrist, palms, knees, wrist, palms, knees, etc. to secure skin to etc. to secure skin to deep tissuedeep tissue

Eccrine sweat glandsEccrine sweat glands - primarily for - primarily for thermoregulationthermoregulation

Sebaceous glandsSebaceous glands - - oiloil

DevelopDevelop in utero in utero ~13-15 weeks of gestation

Ridges are unique and permanentRidges are unique and permanent The patterns never changes

except in size

Print left by secretions from Print left by secretions from pores in the ridgespores in the ridges

18 major components18 major components– Primarily water, amino acids + Primarily water, amino acids +

saltssalts– Some oilsSome oils

General features of all General features of all printsprints

Ridges / ridge Ridges / ridge lineslines – raised – raised part of the skin, part of the skin, ~150 per finger~150 per finger

FurrowsFurrows – – lowered skinlowered skin

MinutiaeMinutiae – – small, unique small, unique ridge ridge characteristicscharacteristics

DeltaDelta – point – point where 3 ridge where 3 ridge lines meet in a lines meet in a triangletriangle

CoreCore – center of – center of the fingerprintthe fingerprint

General classificationsGeneral classifications

LoopsLoops– 60-70% of the population60-70% of the population

WhorlsWhorls– 25-35%25-35%

ArchesArches– 5%5%

LoopsLoops

One or more of the ridges One or more of the ridges enters on one side of the enters on one side of the impression impression

recurves recurves touches or crosses the line touches or crosses the line

running from the delta to running from the delta to the core the core

and terminates one the and terminates one the same side where the same side where the ridges enteredridges entered

There is one delta. There is one delta. The number of ridge lines The number of ridge lines

forming the loop is an forming the loop is an identifying characteristic identifying characteristic tootoo

Types of loopsTypes of loops

Two bones in the Two bones in the lower armlower arm

Radius - attaches Radius - attaches to wrist/hand to wrist/hand closest to the closest to the thumbthumb

Ulna – attaches Ulna – attaches closest to little closest to little fingerfinger

Radial loopRadial loop– Ridge lines enter/exit on the side of the Ridge lines enter/exit on the side of the

finger pointing towards the thumbfinger pointing towards the thumb– Not commonNot common

Ulnar loopUlnar loop– Ridge lines enter/exit on the side of the Ridge lines enter/exit on the side of the

finger pointing towards the little fingerfinger pointing towards the little finger

WhorlsWhorls

2 or more deltas2 or more deltas

Types of WhorlsTypes of Whorls

Plain whorlPlain whorl

Consists of one or more Consists of one or more ridges which make or tend to ridges which make or tend to make a complete circuit, with make a complete circuit, with 2 deltas2 deltas

If an imaginary line is drawn If an imaginary line is drawn between deltas, there is at between deltas, there is at least one recurving ridge least one recurving ridge within the inner pattern area within the inner pattern area that is cut or touched.  that is cut or touched. 

At least one type line forms a At least one type line forms a circlecircle

Central pocket whorlCentral pocket whorl

Consists of one or a few Consists of one or a few ridges which make or tend ridges which make or tend to make a complete to make a complete circuit, with 2 deltascircuit, with 2 deltas

If an imaginary line is If an imaginary line is drawn NO recurving ridges drawn NO recurving ridges within the inner pattern within the inner pattern are cut or touched.are cut or touched.

At least one type line At least one type line forms a circleforms a circle

Double loop whorlDouble loop whorl

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

Accidental whorlAccidental whorl

Contains 3 or Contains 3 or more deltasmore deltas

ArchesArches

Ridges run from one side to the Ridges run from one side to the other, making no backward turn.other, making no backward turn.

Generally there is no delta + no Generally there is no delta + no significant coresignificant core

If there is a delta recurving ridge If there is a delta recurving ridge must intervene between the core must intervene between the core and delta points. and delta points.

Types of archesTypes of arches

Plain archPlain arch

The overall pattern The overall pattern area tends to just area tends to just flow through the flow through the print with no print with no significant changes significant changes

Types of archesTypes of arches

Tented archTented arch

Contains a Contains a significant significant upthrustupthrust

CompositesComposites

Include Include patterns in patterns in which which combinationcombinations of the s of the tented arch, tented arch, loop and loop and whorl are whorl are found in the found in the same printsame print

Fingerprint ID PracticeFingerprint ID Practice

Assume prints are from the left Assume prints are from the left handhand

A BA B C C

D E F D E F

Plain whorl Ulnar loop Tented archPlain whorl Ulnar loop Tented arch

Plain arch Plain arch Central pocket whorl Double loop Central pocket whorl Double loop whorlwhorl

MinutiaeMinutiae

Unique identifying pointsUnique identifying points FBI requires 8 for a positive IDFBI requires 8 for a positive ID

– Ranges from 5-12 in different statesRanges from 5-12 in different states

Types of minutiaeTypes of minutiae

Ridge Ridge endingending

Bifurcation/ Bifurcation/ TrifurcationTrifurcation

DotDot

IslandIsland– Ridge lineRidge line

Lake Lake – EnclosureEnclosure

CrossoverCrossover

BridgeBridge

EllipseEllipse

SpurSpur

Fingerprint ID Fingerprint ID techniquestechniques

1. Take a ten-1. Take a ten-printprint– ID general ID general

classification for classification for each fingereach finger

Fingerprint ID Fingerprint ID techniquestechniques 2. Balloon print of right index 2. Balloon print of right index

fingerfinger– ID general classificationID general classification– ID as many different types of ID as many different types of

minutiae as possibleminutiae as possible

Types of prints found Types of prints found in the environmentin the environment LatentLatent

– Formed by oil + sweat deposited by a Formed by oil + sweat deposited by a person’s fingers when they touch a surfaceperson’s fingers when they touch a surface

– Invisible to the naked eye, must be Invisible to the naked eye, must be developeddeveloped

VisibleVisible– Prints contaminated with blood, ink, etc. Prints contaminated with blood, ink, etc.

that leave visible printsthat leave visible prints Plastic (molded)Plastic (molded)

– Impression left in a soft substance (i.e. Impression left in a soft substance (i.e. soap, wax)soap, wax)

Latent print detectionLatent print detection

1. Dusting powders1. Dusting powders– NormalNormal

Grey vs. blackGrey vs. black

– MagneticMagnetic– FluorescentFluorescent

Good for hard or Good for hard or non-absorbent non-absorbent surfacessurfaces

2. Cyanoacrylate 2. Cyanoacrylate fumingfuming

Turns a latent Turns a latent print into a print into a permanent visible permanent visible print (arrested print (arrested print)print)

Good for plastics Good for plastics + metals+ metals

3. Iodine 3. Iodine fumingfuming

Good for paperGood for paper

4. Ninhydrin 4. Ninhydrin sprayspray

Good for Good for paper, reacts paper, reacts with amino with amino acid residues acid residues in sweatin sweat

5. Silver nitrate (physical 5. Silver nitrate (physical developers)developers)

Good for porous surfaces like Good for porous surfaces like currency, wood + cardboard, currency, wood + cardboard, recognizes lipidsrecognizes lipids

Methods of Methods of ComparisonComparison

Henry Primary Classification SystemHenry Primary Classification System Calculate the value given the following equation:Calculate the value given the following equation:

Pair #Pair #

1 2 3 4 51 2 3 4 5

R. Index + R. Ring + L. Thumb + L. Middle + L. Little R. Index + R. Ring + L. Thumb + L. Middle + L. Little + 1+ 1

R. Thumb + R. Middle + R. Little + L. Index + L. Ring R. Thumb + R. Middle + R. Little + L. Index + L. Ring + 1+ 1

Numerical value assigned to any Numerical value assigned to any WHORLWHORL in the numerator or in the numerator or denominatordenominator

Pair 1 = 16Pair 1 = 16 Pair 2 = 8Pair 2 = 8 Pair 3 = 4Pair 3 = 4 Pair 4 = 2Pair 4 = 2 Pair 5 = 1Pair 5 = 1

ARCHESARCHES and and LOOPSLOOPS = 0 = 0

ExampleExample

Whorls ID’d in right index and left index Whorls ID’d in right index and left index fingersfingers

Arches or loops everywhere elseArches or loops everywhere else What is the Primary Classification value?What is the Primary Classification value?

Remember:Remember:R. Index + R. Ring + L. Thumb + L. Middle + L. Little + 1R. Index + R. Ring + L. Thumb + L. Middle + L. Little + 1R. Thumb + R. Middle + R. Little + L. Index + L. Ring + R. Thumb + R. Middle + R. Little + L. Index + L. Ring +

11

ExampleExample

R. IndexR. Index + R. Ring + L. Thumb + L. Middle + L. Little + R. Ring + L. Thumb + L. Middle + L. Little + 1+ 1

R. Thumb + R. Middle + R. Little + R. Thumb + R. Middle + R. Little + L. IndexL. Index + L. Ring + L. Ring + 1 + 1

16 + 0 + 0 + 0 + 0 + 116 + 0 + 0 + 0 + 0 + 1 = = 1717

0 + 0 + 0 + 2 + 0 + 10 + 0 + 0 + 2 + 0 + 1 = 3= 3

AFISAFIS – Automated fingerprint – Automated fingerprint identification systemidentification system

Computer scanners identify Computer scanners identify ridge ridge endings and bifurcations endings and bifurcations only, and only, and their relative positions are mapped their relative positions are mapped

Prints lifted at the crime scene are Prints lifted at the crime scene are compared to fingerprints on file compared to fingerprints on file

A group of suspect fingerprint cards is A group of suspect fingerprint cards is identified identified

An examiner does a point by point An examiner does a point by point comparison comparison

The computer can compare the The computer can compare the suspect's print to 500,000 fingerprint suspect's print to 500,000 fingerprint cards in less than a second cards in less than a second

Computer enhancement can also Computer enhancement can also compensate for imperfections in lifted compensate for imperfections in lifted latent printslatent prints