fingerprints

evidence recovery destructive techniques

• Search and recovery of latent evidence

• Introduction of contaminants

• Powders and chemicals

• Focus on fingerprint and footwear evidence

friction ridge details

• fingerprints are made up of ridges, furrows and thousands of tiny sweat spores

• assist sense of touch

• ridges cause friction which allow for grip

fingerprint patterns - Loop

• 65% of fingerprints

• sufficient recourse

• one delta

• ridge count of at least one between the delta and core

fingerprints patterns - Nutant loop

• the course of the loop bends, turns down other drops towards the delta

fingerprint patterns - Ulnar

• 94%

• when the loop enters and exits from the little finger side of the hand

fingerprint patterns - Radial

• 6%

• when the loop enters and exits from the thumb side of the hand

fingerprint patterns - plain arch

• ridges run from side to side

• no delta

fingerprint patterns - tented arch

• ridges near the centre have an upwards thrust

• appears as the tent in outline

fungerprint pattern - whorl

• 30%

• at least on circuit of ridge formation completes 360

• circuit may be formed from a continuously flowing ridge or by segments from several ridges

• 2 deltas

fingerprint patters - twinned loop

• 2 well defined loops

• one surrounding the other

fingerprint patterns - lateral pocket

• 2 loops with the same directional shape

• the uppermost loop nutant, forming a pocket, filled by the underlying loop

fingerpint pattern - composite

• a complicated combination f patterns with 3 or more deltas

fingerprint patterns - accidental

• a minority pattern which does not conform to the arch, loop of whorl types

• possesses characteristics common to all 3 types

how are items deposited

• deposited onto an item in a contaminant

• impresses into an item

• deposited into an item in sweat

search and recovery

• initially conduct a visual examination

• photograph scene and location of fingerprints

• impresses fingerpints

• laten fingerprints

latent marks

• quality of the print depends on surface, pressure, age, time and storage

• powders - metalic flake, granular, magnetic

• brushes - carbon/glass fibre, animal hair, feather, synthetic, magnetic wand

• lifting medium - codex sheet, template, scalpel, touch, permanent pen, roller

laten mark examination

• fingerpints to be done after DNA and trace evidence examination completed

• work cleanly, keeping damage to a minimum

• photograph all locations of fingerprints before lifting, recovering

• would not leave own prints as wearing gloves

• start at the point go entry and be systematic