Fingerprints

fingerprints in forensics

Used to identify individuals by unique ridge patterns

fingerprint science

Respected forensic method for personal identification

friction ridge skin

Specialized skin on fingers palms and soles that forms fingerprints

oldest fingerprint evidence

6000-year-old ridge impressions on pottery

ancient fingerprint use

Used for decoration signatures or symbols

China fingerprints

First culture to use fingerprints for identification

Qin Dynasty fingerprints

Used handprints as legal evidence

clay seals

Fingerprints pressed into clay to verify identity

ink fingerprints

Used on contracts wills and records in China

fingerprint individuality ancient

Early belief that fingerprints are unique

William James Herschel

First European to use fingerprints for identification

Herschel first use

Used handprint instead of signature in 1858

Herschel discovery

Fingerprints are unique and permanent

Herschel contribution

Recommended fingerprints to prevent fraud

Herschel 1877

Required fingerprinting of pensioners and criminals

Herschel book

The Origin of Fingerprinting 1916

Francis Galton

Created first fingerprint classification system

Galton patterns

Named whorl loop and arch

Galton book

Finger Prints 1892

Juan Vucetich

Pioneer of fingerprinting in the Americas

Vucetich achievement

Identified murderer using fingerprint in 1892

Vucetich book

Comparative Dactyloscopy 1904

Henry P de Forest

First systematic fingerprint use in US

de Forest 1902

Fingerprinted civil service applicants

Henry System

Fingerprint system adopted in US

AFIS

Automated fingerprint identification database

AFIS purpose

Stores and compares fingerprint images

1903 fingerprint use

Adopted in criminal identification

1904 training

Police trained by Scotland Yard

1924 FBI records

Fingerprint databases merged

fingerprint legality early

Initially challenged in court

People v Jennings 1911

First case allowing fingerprint evidence

Jennings evidence

Fingerprint match in paint

People v Crispi

First US conviction using only fingerprints

Daubert challenge 1998

Questioned fingerprint validity

People v Mitchell

Upheld fingerprint reliability

fingerprint individuality modern

Considered unique and permanent

comparison evidence

Requires known and unknown samples

identical twins fingerprints

Even twins have different prints

fingerprint limitation

Uniqueness not absolutely proven

modern fingerprint use

Used for criminals jobs and security

post WWII fingerprinting

Became standard after arrests

fingerprint formation start

Begins around week 12 of development

fingerprint formation complete

Finished by week 16

fingerprint permanence

Remain same except scars or aging

developmental noise

Random factors causing unique prints

ridge

Raised part of fingerprint

valley

Indented groove between ridges

skin layers

Epidermis dermis hypodermis

epidermis

Outer protective layer

dermis

Middle layer with nerves and blood vessels

hypodermis

Fat layer for energy and support

sweat glands

Only appendage in friction ridge skin

sweat function

Leaves residue for fingerprints

sweat composition

Water salts oils and waste

aging fingerprints

Ridges flatten and skin wrinkles

scars fingerprints

Add unique identifying features

basic fingerprint patterns

Arch loop whorl

pattern percentages

Loops 60 percent whorls 35 percent arches 5 percent

delta

Triangle point where ridges split

arch

Ridges enter one side exit other no delta

plain arch

Smooth arch shape

tented arch

Sharp spike in center

loop

Ridges enter and exit same side one delta

ulnar loop

Opens toward pinky

radial loop

Opens toward thumb

whorl

Circular pattern with two deltas

plain whorl

Ridges touch imaginary line

central pocket whorl

Ridges do not touch line

double loop whorl

Two loops combined

accidental whorl

Irregular mixed pattern

first analysis step

Identify overall fingerprint pattern

minutiae

Small ridge details that make prints unique

bifurcation

Ridge splits into two

ridge ending

Ridge stops

enclosure

Ridge splits then rejoins

ridge dot

Tiny dot-like ridge

crossover

Ridges cross in X shape

island

Small short ridge

bridge

Ridge connects two ridges

double bifurcation

Ridge splits twice

triple bifurcation

Ridge splits three times

average minutiae

About 150 per print

minutiae match

8 to 16 needed for identification

substrate

Surface where print is found

porous surface

Absorbs moisture like paper

semi porous surface

Partially absorbs moisture

non porous surface

Does not absorb moisture like glass

matrix

Substance forming the print

natural matrix

Sweat and oils

foreign matrix

Blood ink or grease

patent print

Visible print from colored material

plastic print

Impression in soft material

latent print

Invisible print from sweat and oils

fingerprint powder

Sticks to oils to reveal prints

black powder

Best for light surfaces

gray powder

Best for dark surfaces

fluorescent powder

Used on multicolor surfaces

magnetic powder

Used with magnetic brush

lifting prints

Use tape to remove print