Trace Evidence Test

Anagen

active phase of hair growth cycle - 2 years

Catagen

transition phase of hair cycle - 10 days

Telogen

End stage of hair growth cycle - 3months

Cortex

Located outside the medulla and contains the pigment

Cuticle

Outermost layer of hair, tough covering composed of overlapping dead skin cells that make scales (colorless)

Medulla

innermost layer of hairshaft

Medullary Indec

Ration of medulla diameter- medulla diameter/shaft diameter (<.33 = human, >.5 - animal)

Follicle

Growing base of a hair that has DNA and living cells

Root

in the hair follicle and contains the DNA

shaft

structure of the 3 layers in hair

scales

patterns of a cuticle

Cortical Fusi

small air spaces that form between hair shaft

Plain (weave)

strong, hard, and natural

twill (weave)

pattern - diagnol ribs/parallel natural

satin (weave)

glossy, smooth, and natural

warp

yarn running vertically pattern

weft

yarn running sideways across other threads

float

float test in water

selvage

edge on either side woven or knit to prevent unraveling

synthetic

Man made materials through chemical synthesis

Locards principle

every contact leaves a trace

probative value

probability of evidence to reach proof purpose

morphology

study of shapes/arrangement of organisms

class evidence

evidence that fits a broad group

individual evidence

evidence that only fits one person

frye standard

generally accepted within scientific community

daubert ruling

systematic framework of a trial court judge

associative value

changes or disappears over time

keratinization

process which soft and pliable cells transform into rigid, tough, and durable cells

melanin

produces pigment in hair, eyes, and skin

birefrigence

material having a refractive index

DNA from root

cells that create the root

DNA from shaft

cells that create the shaft

delustering particles

particiles determined through microscopic, chemical analysis

amorphous

having no definite shape or form

becke line

halo observed near boundary of a transparent particle

3R rule

radial cracks form right angles on the reserve side of force

conchodial fracture

break of a brittle material that doesn’t follow any natural planes of seperation

radial fracture

cracks that run outward from point of impact

concentric fracture

arc-shaped or circular crack that loops around point where an impact struck

tempered glass

glass processed by controlled thermal/chemical treatments - phones and windows

laminated glass

glass containing two or more layers of glass - glass floors or animal enclosures

binder

polymeric component holds pigment particles together and bonds

pigment

finely grang, inorganic, insolubke particle

electrocoat primer

method of painting that uses electrial current to deposit paint on surface

PDQ (Paint Database)

records automotive paint samples

Py-GC

thermal decomp of materials at high temperature

diatoms

single celled algae made of silica

palynology

study of plant pollen and spores

dendrochronology

study of rings of trees

forensic geology

materials found in earth used as evidence