fingerprints

sir francis galton

found fingerprints were unique and dont change with age

ivan vucetich

first practical use by law enforcement

sir edmund henry

developed own classification system based on pattern types

AFIS

automatic fingerprint identification system; ability to store millions of fingerprints and search for them in minutes

biology of fingerprints

Volar pads (swelling of underlying tissue on hands and feet) begins about the 6th week)

Friction ridges begin to form about 10th week of gestation

3 layers of skin

Epidermis (Outermost protective layer)

Dermis (Middle layer, Provides elasticity)

Hypodermis (Innermost layer)

Basal layer of epidermis

single layer of cells

alive and reproducing

cells migrate to the surface (30 days)

Top layer contains 25-30 layers of dead, flattened skin cells that continually slough off

changing fingerprints

injuries to skin wont change fingerprints; if basal layer is damaged then there is new ridges developing

fingerprint residue

natural secretions, environment, eccrine glands, sebaceous glands

patent fingerprint

visible prints

plastic fingerprint

actual indentations left in soft material like clay

latent fingerprint

most common; hidden prints can be made visible by use of powder or chemicals

ACE-V

Analysis

Comparison

Evaluation

Verification

The examination method used in forensic identification

core

center most print

delta

triangular area where ridges extend in 3 directions

ridge count

number of ridges between the core and the delta; dont count core or delta

loop pattern type

65% of population. exit on the same side entered

whorl

30% of population has whorls; series of concentric circles

arch

5% of the population; ridges enter on one side of the print, exit on the other

minutiae

unique small details

bifurcation

The point where one ridge divides, or forks, and splits into two ridges (like letter Y)

dot

a ridge that is a big as it is wide

ending ridge

a ridge that stops within the ridge structure

enclosure (island)

the point where one ridge splits, becomes two for a short time, then comes back together

pores

Can vary in size and shape (round, oval, square) or resemble a notch on the edge

edges

Can be affected by various factors (pressure, dev. agents, foreign material) so it's difficult to make matches

photography for collecting prints

Photographed in situ (in its original place and state)

fingerprint powder

Fingerprint powders are fine powders used in dusting for prints by CSI’s.

magnetic powder

the powder is attracted by the magnet in the head of the magnetic brush, causing the iron particles to form a kind of brush.

superglue

Produces a visible, sticky white material that forms along the ridges of the fingerprint

alternative light source

Use to enhance the appearance of a fingerprint

ninhydrin

Typically used with paper and other porous surfaces

Reacts with latent print residue like amino acids

Produces a purple color

why no prints?

Surface (porous vs non porous)

Barriers

Temperature (heat and cold) and humidity

Light and water