FingerprintsFingerprints

FingerprintingFingerprinting System of identification based on System of identification based on

the classification of finger ridge the classification of finger ridge patternspatterns

Fundamental Fundamental Principles of Principles of FingerprintsFingerprints1.1. No two persons have identical No two persons have identical

ridge patterns.ridge patterns.2.2. A fingerprint remains unchanged A fingerprint remains unchanged

during a person’s lifetime.during a person’s lifetime.3.3. Fingerprints have general ridge Fingerprints have general ridge

patterns that can be patterns that can be systematically classified.systematically classified.

What are Fingerprints?What are Fingerprints? An impression left on An impression left on

any surface that consists any surface that consists of patterns made by the of patterns made by the ridges on a fingerridges on a finger

RidgeRidge: appears dark in : appears dark in an imagesan images

ValleyValley: appears light in : appears light in an image an image

ActivityActivityGiant Balloon FingerprintsGiant Balloon Fingerprints

Human SkinHuman Skin

The epidermis (outer layer) and The epidermis (outer layer) and dermis (inner layer) determine the dermis (inner layer) determine the form and pattern of ridges on the form and pattern of ridges on the surface of skinsurface of skin

Fingerprints develop in the human Fingerprints develop in the human fetus (starting the 10fetus (starting the 10thth week) week)

Other prints: palms of the hands, Other prints: palms of the hands, soles of feet, lips, earssoles of feet, lips, ears

Ten CardTen Card A form used to record and A form used to record and

preserve a person’s fingerprintspreserve a person’s fingerprints

Activity: Making a Activity: Making a Ten CardTen CardUse ink strips to print each Use ink strips to print each finger on the handout finger on the handout provided.provided.

Fingerprint PatternsFingerprint Patterns

Three classes:Three classes:• LoopsLoops• WhorlsWhorls• ArchesArches

Fingerprint DataFingerprint Data

FingerpriFingerprint Typent Type

Total Total ##

ClassrooClassroom Total m Total

##ClassrooClassroo

m %m %National National PopulatioPopulatio

n (%)n (%)

LoopLoop

WhorlWhorl

ArchArch

National Fingerprint National Fingerprint DataData

National Population:National Population:• Loops (65%)Loops (65%)• Whorls (30%)Whorls (30%)• Arches (5%)Arches (5%)

Fingerprint Fingerprint PatternsPatterns

Ridge CharacteristicsRidge Characteristics

MinutiaeMinutiae MinutiaeMinutiae: points where print ridges : points where print ridges

come together or endcome together or end Minutiae points considered to be Minutiae points considered to be

the “uniqueness” of an individualthe “uniqueness” of an individual Also called “Points”Also called “Points” FBI have found that no two FBI have found that no two

individuals have more than 8 individuals have more than 8 common “Points”common “Points”

Minutiae PointsMinutiae Points

Latent FingerprintsLatent Fingerprints

Activity: Make a Activity: Make a Latent PrintLatent PrintFollow instructions to make a Follow instructions to make a latent print on a clean latent print on a clean surface.surface.

Types of FingerprintsTypes of Fingerprints

Patent (Visible) PrintPatent (Visible) Print Impressed (Plastic) PrintImpressed (Plastic) Print Latent PrintLatent Print

Patent (Visible) PrintPatent (Visible) Print Finger comes in contact with Finger comes in contact with

medium (blood, dirt, ink, grease) medium (blood, dirt, ink, grease) and leaves visible impressionand leaves visible impression

Plastic (Impressed) Plastic (Impressed) PrintsPrints Indentations left in clay, wax, Indentations left in clay, wax,

paint, soap, putty or other soft paint, soap, putty or other soft pliable surfacespliable surfaces

Can be viewed or photographedCan be viewed or photographed

Latent PrintLatent Print Fingerprint made by the deposit Fingerprint made by the deposit

of oils and/or perspirationof oils and/or perspiration Invisible to the naked eyeInvisible to the naked eye Made visible by dusting, fuming Made visible by dusting, fuming

or other chemical reagentsor other chemical reagents

Detection of Latent Detection of Latent PrintsPrints Fingerprint powders (colored, Fingerprint powders (colored,

magnetic, fluorescent dyes)magnetic, fluorescent dyes) Iodine FumingIodine Fuming NinhydrinNinhydrin Cyanoacrylate (superglue) fumingCyanoacrylate (superglue) fuming Silver NitrateSilver Nitrate

Detection of Latent Detection of Latent PrintsPrints

Studying a Latent Studying a Latent PrintPrint

Studying a Latent Studying a Latent FingerprintFingerprint

1.1. Using the fingerprint brush and Using the fingerprint brush and powder, lightly dust the powder, lightly dust the fingerprint (use a circular motion)fingerprint (use a circular motion)

2.2. Press and lift the print off of the Press and lift the print off of the surface using clear tape.surface using clear tape.

3.3. Tape your latent print into your Tape your latent print into your lab notebook.lab notebook.

4.4. Identify your print pattern as Identify your print pattern as either a loop, arch or whorl.either a loop, arch or whorl.

Automated Fingerprint Automated Fingerprint Identification System Identification System (AFIS)(AFIS)

In 1999, state AFIS In 1999, state AFIS computers were fully computers were fully linked with the FBI linked with the FBI databasedatabase

Contains nearly 50 Contains nearly 50 million fingerprint recordsmillion fingerprint records

Each fingerprint scanned; Each fingerprint scanned; digital minutiae data digital minutiae data stored in computerstored in computer

How is AFIS used?How is AFIS used?

1.1. Unknown print is scanned Unknown print is scanned and entered into computerand entered into computer

2.2. Computer searches AFIS Computer searches AFIS system and produces a list of system and produces a list of file prints that match closest file prints that match closest with search print (takes 2 with search print (takes 2 hours)hours)

3.3. Fingerprint expertFingerprint expert examines examines prints and makes final prints and makes final verification on print’s identifyverification on print’s identify

Mobile Mobile Fingerprint Fingerprint IdentificationIdentificationUsed by police Used by police officers in the field to officers in the field to search AFIS and get search AFIS and get a positive a positive identification on a identification on a suspect.suspect.

Fingerprint FAQsFingerprint FAQs Fingerprints dissolved by acid will Fingerprints dissolved by acid will

grow backgrow back Scars on fingers make prints even Scars on fingers make prints even

more uniquemore unique