90+% of the information in this presentation was taken directly from Fingerprints 90+% 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. Uniqueness All Fingerprints are different Nature does not repeat any object in complete detail. Permanence Fingerprint patterns remain constant as a person matures. Superficial skin damage grows back to original 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 accepted method The generally accepted method for friction ridge individualization

RIDGE Detail 1st Level Detail 2nd Level Detail 3rd 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.

Classification Ya 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 Deltas If 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%) Loops only have one delta. They also have one core. Core Delta

Arm Bones Radius – on thumb side; thick near wrist Ulna

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.