Fingerprints90+% of the information in this presentation was taken

directly from

http://www.brazoria-county.com/sheriff/id/fingerprints/index.htm

Ancient History is a mystery

• Suggested that thumbprints on Babylonian clay tablets and ancient Chinese clay seals were deliberately placed there as identifying marks

Sir Francis Galton• Established that

fingerprints are unique.

• Wrote book Fingerprints

• This introduced modern techniques of criminal investigation, replacing tatooting, branding, and body measurements as methods of identifying criminals.

(Charles Darwin’s Cousin)

Galton’s Premises(or Galton Details)First to categorize minutia and observe that they remain unchanged.

1.Uniqueness1. All Fingerprints are different

2. Nature does not repeat any object in complete detail.

2.Permanence1. Fingerprint patterns remain constant as a person

matures.

2. Superficial skin damage grows back to original

3. Severe cuts and resulting scars remain permanent.

Sir Edward Richard Henry• Developed a method of

indexing fingerprints = Henry Classification System.• Problem: need all 10

prints• Book: Classification and

Uses of Fingerprints– Classifies fingerprints into

three types: Arches, Loops, and Whorls

Johannes Purkinje• In his doctoral thesis, he

identified nine print patterns:• Arch• Tented arch• Loop• Six Whorls

The basic tenets of friction skin identification are:

Friction skin is UNIQUE

Friction skin develops before birth, is PERMANENT and NEVER

CHANGES

Variation in ridge patterns vary within specific limits and can be classified.

ACE-V

• Analysis

• Comparison

• Evaluation

• Verification

The generally accepted

method for friction ridge individualization

RIDGE Detail

1st Level Detail1st Level Detail

2nd Level Detail2nd Level Detail

3rd Level Detail3rd Level Detail

Where to look for minutiae

The area immediately surrounding a delta will probably contain more points per square millimeter than the area near the tip of the finger which tends to not have that many points.

Finding Minutiae

These are only 10 of the 22 in this ¼ X ¼ inch section.

Finding Minutiae

• May not be all that easy. In real life, impressions– are made at separate times. – are subject to different pressure distortions.– from a crime scene are anything but clear. – from a crime scene could be a fingertip,

palm or even foot impression, not the core of a fingerprint.

ClassificationYa gotta be able to find

the delta(s) or recognize a lack of them!

Deltas = a place where two

lines run side-by-side and then diverge with a significant recurving line that passes in front of the delta.

Classification Based on DeltasIf the print has one

delta then the pattern is a loop.

If the pattern has more than 1 delta then it is a whorl.

If the pattern has no delta's then it is an arch.

Simple enough so long as you can effectively identify the deltas.

Classification: Loops (65%)

CoreLoops only have one delta.

They also have one core.

Delta

Arm Bones

Ulna

Radius – on thumb side; thick near wrist

Ulnar and Radial Loops

If on left hand, comes in and goes out from pinky side = ulnar side

=

ulnar loop

If on right hand, comes in and goes out from thumb side =

radial side =

radial loop

Plain Arch

No delta

No significant core

Tented Arch

Has a "significant upthrust"

No, that’s not a delta. To be a valid delta there has to be a significant recurving line that passes in front of the delta

Plain Whorl

• Must be more than one delta

• Must intersect lines that make up the whorl when you draw a straight line between the deltas.

Are these plain whorls?

Central Pocket Whorl

The ridges that form the inner pattern of the whorl are not crossed by an imaginary line drawn between the two deltas.

Accidental Whorl

Is a pattern not covered by other categories, or is a combination (e.g., loop and plain whorl or loop and tented arch).

Double Loop Whorl

• Has two separate and distinct loop formations with two separate and distinct shoulders and two deltas

Double Loop Whorl

• The shoulders of each "core" must comprise separate lines.

Double Loop Whorl

• The shoulders of each "core" must comprise separate lines.

• Here they don’t.