Glass and Physical Evidence

Question 1

Glass applications and manufacturing

Answer 1

• made from sand, silica, soda ash, limestone, boron or led
• flat (float-tin) on vehicles and architecture
• container glass is floated, plus ions for color

Question 2

Strengthening

Answer 2

• Annealed: not strengthened
• tempered: strengthened
• laminated: bullet proof
• wired: schools, hospitals

Question 3

Types of Fractures

Answer 3

Thermal: meandering cracks, no poi
Impact: poi with radial cracks
Low velocity: stretched on opposite side (4R)
High Velocity: coning effect, large opening
- 4R: Ridge lines on Radial fractures are at Right angle to the Rear

Question 4

Glass as trace evidence

Answer 4

• small fragments may be transferred to people and objects
• tested based on appearance, brittleness, UV fluorescence, polarized light microscopy, refractive index

Question 5

the principle of discernable uniqueness

Answer 5

Markings from different people and objects will be different - Quetelet

Question 6

Identification stages

Answer 6

1 - are question and known indistinguishably alike
2 - the extent of indistinguishability

Question 7

Soil as trace evidence

Answer 7

any disintegrated material located on or near the earths surface, should be dried and packaged in a box

Question 8

Hair Biology

Answer 8

• composed of keratin
• 3 sections:
  the cuticle - scaly layer over shaft
  the medulla - innermost layer, no cell material in humans
  the cortex - between cuticle and medulla, contains pigment
• DNA is extracted from the root, appearance may determine race

Question 9

Phases of hair growth

Answer 9

anagen - follicle growth
telogen - follicle dormant

Question 10

collection of hair

Answer 10

Head:
- at least 50 hairs, cut at surface
Pubic
- at least 20, cut at surface
Deceased:
- double the amount and pluck
- package in envelopes, secondary packaging for unknowns