Upload
darleen-long
View
246
Download
2
Tags:
Embed Size (px)
Citation preview
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