fingerprinting

FingerprintingFingerprinting

Why do we have Why do we have fingerprints?fingerprints?

““Friction Ridge SkinFriction Ridge Skin”” Provides a firm grasp & resists slippage.Provides a firm grasp & resists slippage.

►Found on the palm side of fingers & hands, Found on the palm side of fingers & hands, soles of feet and toes.soles of feet and toes.

►Formation occurs during Formation occurs during fetal developmentfetal development.. Fingerprints do Fingerprints do NOTNOT change over a lifetime. change over a lifetime. Identical twins have Identical twins have differentdifferent fingerprints! fingerprints! Fingerprints grow back when damaged.Fingerprints grow back when damaged.

Three (3) Types of Three (3) Types of FingerprintsFingerprints

►LatentLatent Invisible fingerprints.Invisible fingerprints. Formed when sweat, oil, amino acids, & Formed when sweat, oil, amino acids, &

water are deposited in the formation of water are deposited in the formation of the ridge pattern.the ridge pattern.

►PlasticPlastic Impressed into soft materials.Impressed into soft materials.

►Gum, wax, soap, dust, putty, etc…Gum, wax, soap, dust, putty, etc…

►Visible or PatentVisible or Patent Fingerprint left in a visible material Fingerprint left in a visible material

►Ink, grease, blood, paint, etc…Ink, grease, blood, paint, etc…

Fingerprint CompositionFingerprint Composition

►SweatSweat Eccrine sweat glandsEccrine sweat glands

►Produce a “watery” sweat.Produce a “watery” sweat.

Apocrine sweat glandsApocrine sweat glands►Produce an “oily” sweatProduce an “oily” sweat

►ProteinsProteins►LipidsLipids

Skin AnatomySkin Anatomy

►EpidermisEpidermis Top Layer of Skin (2 mm in fingers)Top Layer of Skin (2 mm in fingers) Contains keratin, melanin, & immune cells.Contains keratin, melanin, & immune cells.

►DermisDermis Thick layer of connective tissue.Thick layer of connective tissue. Contains blood vessels, nerves, muscles, oil Contains blood vessels, nerves, muscles, oil

& sweat glands, & hair follicles.& sweat glands, & hair follicles.►PapillaePapillae

Boundary between layers; forms ridge Boundary between layers; forms ridge pattern.pattern.

Papillae

Major Ridge PatternsMajor Ridge Patterns

►LoopsLoops ►WhorlsWhorls►ArchesArches

LOOPSLOOPS

►60%60% of population. of population.►Two (2) or more ridges entering from one Two (2) or more ridges entering from one

side, curving and exiting on the same side.side, curving and exiting on the same side. CoreCore

►Center of loopCenter of loop

Type LinesType Lines ►Ridges that divergeRidges that diverge

DeltaDelta ►Closest ridges to type lines; Closest ridges to type lines;

forms a triangle.forms a triangle.

Anatomy of a LoopAnatomy of a Loop

Types of LoopsTypes of Loops►Radial LoopRadial Loop

Loop opens towards Loop opens towards thumb.thumb.

►Ulnar LoopsUlnar Loops Loop opens towards Loop opens towards

pinkie.pinkie.

WHORLSWHORLS

►30%-35%30%-35% of population. of population.►Must have type lines and a Must have type lines and a minimumminimum

of two (2) deltas!of two (2) deltas!►Four types:Four types:

Plain WhorlPlain Whorl Center Pocket WhorlCenter Pocket Whorl Double Loop WhorlDouble Loop Whorl Accidental Accidental

Types of WhorlsTypes of Whorls► Plain WhorlPlain Whorl ► Center Pocket Center Pocket

WhorlWhorl

Plain vs. Center Pocket Plain vs. Center Pocket WhorlsWhorls

►Both have at least one ridge that Both have at least one ridge that makes a makes a complete circuitcomplete circuit..

Draw a line through the deltas. Center Pocket line does NOT touch circuit ridge!

Plain – hits the circuit ridge.

Types of WhorlsTypes of Whorls

►Double Loop Double Loop WhorlWhorl

►AccidentalAccidental

ARCHESARCHES

►5%5% of population. of population.►SimplestSimplest of all fingerprints! of all fingerprints!►Ridges enter on one side of print and Ridges enter on one side of print and

exit on the other.exit on the other. Slight or dramatic rise in the center.Slight or dramatic rise in the center. Plain Arch vs. Tented ArchPlain Arch vs. Tented Arch

►No type lines or deltas.No type lines or deltas.

Types of ArchesTypes of Arches

► Plain ArchPlain Arch ► Tented ArchTented Arch

Fingerprint AnalysisFingerprint Analysis►Used to match a suspect to a crime scene.Used to match a suspect to a crime scene.

►NotNot based upon general shape or pattern. based upon general shape or pattern.

►Requires a point by point match of Requires a point by point match of minutiae.minutiae.

►Average fingerprint has Average fingerprint has 150 minutiae150 minutiae.. 8 to 16 matches8 to 16 matches adequate in court. adequate in court. No statistical studies regarding locations of No statistical studies regarding locations of

common minutiae in populations.common minutiae in populations.

MinutiaeMinutiae

►RidgesRidges – raised points on a print. – raised points on a print.►GrovesGroves or or Furrows Furrows – low points on a – low points on a

print.print.

Minutiae (Ridge characteristics)Minutiae (Ridge characteristics)►Ridge EndingsRidge Endings►Short RidgeShort Ridge►BifurcationBifurcation►Island or DotIsland or Dot►Enclosure (or Lake)Enclosure (or Lake)►CrossoverCrossover

Minutiae MappingMinutiae Mapping

Comparing Minutiae MapsComparing Minutiae Maps

Latent Fingerprint RemovalLatent Fingerprint Removal

►Depends upon:Depends upon:

Type of surface Type of surface ►Porous vs. NonporousPorous vs. Nonporous►Soft vs. HardSoft vs. Hard

How the print was left.How the print was left.►Visible vs. Invisible (latent prints)Visible vs. Invisible (latent prints)

Amount of print available.Amount of print available.

Latent Print RemovalLatent Print Removal

►DustingDusting►Superglue FumingSuperglue Fuming►Amino Acid ReactionAmino Acid Reaction► Iodine FumingIodine Fuming

DustingDusting

►Surface:Surface: Smooth, nonporous.Smooth, nonporous.

►Chemical:Chemical: Carbon black powderCarbon black powder

►Method:Method: Dust on powder with brush.Dust on powder with brush. Remove excess powder (puff of air).Remove excess powder (puff of air). ““Lift” print with tape.Lift” print with tape. Place on index card.Place on index card.

Superglue FumingSuperglue Fuming►Surface:Surface:

Smooth, nonporous.Smooth, nonporous.

►Chemical:Chemical: CyanoacrylateCyanoacrylate

►Method:Method: Place print evidence in sealed container.Place print evidence in sealed container. Add few drops of superglue + heat.Add few drops of superglue + heat. Takes 2-3 hours; chemical fumes stick to Takes 2-3 hours; chemical fumes stick to

print.print.

Amino Acid ReactionAmino Acid Reaction►Surface:Surface:

Porous.Porous.

►Chemical:Chemical: NinhydrinNinhydrin

►Method:Method: Spray or dab chemical onto print area.Spray or dab chemical onto print area. Allow to dry (2-3 hours).Allow to dry (2-3 hours). Turns Turns pinkpink when it reacts with proteins. when it reacts with proteins. Highly effective on old prints (up to 15 Highly effective on old prints (up to 15

years!)years!)

Iodine FumingIodine Fuming►Surface:Surface:

Porous.Porous.►Chemical:Chemical:

Iodine crystals (solid)Iodine crystals (solid)►Method:Method:

Place print evidence in sealed container.Place print evidence in sealed container. SublimationSublimation of iodine crystals. of iodine crystals.

►Solid to GAS!Solid to GAS! Vapors attach to print.Vapors attach to print. Not permanent! Must photograph!Not permanent! Must photograph!