types of finger prints (forensics q3)

where do fingerprints come from?

  • dev begins in 10th week of gestation

  • dev completes during 24th week

  • chance, environment, and heredity effect print dev

three principles of fingerprints

  • individual characteristic

    • no two fingers have the same print

    • identical twins have similar prints but not identical

  • remain unchanged during a lifetime

  • general ridge patterns that permit classification

three types of fingerprints

  • plastic impressions

    • made in soft material like butter, soap, etc

  • visible prints

    • made when fingers have been covered in blood, dirt, oil, paint, etc

  • latent prints

    • not visible to human eye until treated

loops

  • 60% of world has them

  • ridges start on one side, rise towards center, and return back to the side they started

  • 1 delta

  • 2 types

    • radial (thumb)

    • ulnar (pinkie)

arches

  • 5% of world has them

  • start on one side, rise towards center, then leave on other side

  • no deltas

  • 2 types

    • plain

    • tented

whorls

  • 35% of world has them

  • some ridges that form circles or spirals

  • 2 deltas

  • 4 types

    • plain

    • central pocket whorl

    • double loop

    • accidental whorl

Pattern Chart

the delta

  • place where lines run side by side and then diverge with a significant recurving line which passes in front of the delta

  • a triangle

core

  • inner part of last ridge

identification of minutiae

  • must find 12 points to match print from scene to person

  • label each with a number and a line to show location

  • make key at bottom of print