11. Trace Evidence Analysis

Question 1

What is trace evidence ?

Name some examples

Answer 1

Very small quantities of materials
Locards principle - every contact leaves a trace
Key examples - hairs fibres and glass fregments

Question 2

Whats inceptive search ?

Answer 2

Extract distinctive material

Question 3

Whats reactive search ?

Answer 3

Looking out for particular material based on other information

Question 4

Name some recovery methods

Answer 4

Shaking
Swabbing
Vacuuming 
Tape-lifting 
Brushing

Question 5

What is naturally shed hair called ?

Answer 5

Telegen

Question 6

What is torn out hair called ?

Answer 6

Anagen

Question 7

What is hair comprised on ?

Answer 7

Keratin

Question 8

What are the racial origins of hair ?

Answer 8

Caucasoid
Mongoloid
Negroid

Question 9

Whats the structure of hair ?

Answer 9

Outside - cuticle
Inside - cortex

Medulla
Cortical fusi
Pigment granule

Question 10

Whats a fibre ?

Answer 10

Smallest unit of a textile which has been spun into thread

Question 11

Why can fibre evidence be individualised ?

Answer 11

Because of the variety of physical and chemical characteristics

Question 12

What are natural fibres ?

Answer 12

Animal fibres ( silk, wool, hair ) vegtable fibres ( linen, cotton, jute, kapok, coir )
mineral fibres ( asbestos )

Question 13

What are organic fibres ?

Answer 13

Synthetic polymers - polyethene,polyamide,polyester

Natural polymers -
Cellulose, materials, rubber

Question 14

What are inorganic fibres ?

Answer 14

Carbon, ceramic, glass, metal

Question 15

How to compare fibres ?

Answer 15

Establish points of identity

Avoud contamination

Question 16

What can a compound microscrope see from fibres ?

Answer 16

Diamater
Shape
Surface features
Colour
Refractive index
Burefringence - determinning chemical nature

Question 17

Stereo microscope

Answer 17

Low magnification

Hairs - classify individualise

Natural fibres - identify classify, finres appearance and distribution

Sumthetic fibres - indentify classfiy fibres appearance and distribution

Question 18

Compoun/polarised microscopy

Answer 18

High magnification
Hair - classify measure identify features

Natural fibres - classify measure indentify features fluorescence

Synthetic fibres - classify and measure fuvres by optical properties, refractive index , birefringence

Question 19

Comparison microcscapy

Answer 19

Manification ranges

Hair - comapre questioned and knows fibres

Question 20

UV visible microspectrophotometry

Answer 20

Characterises colour of the fibre

Question 21

Infared microspectroscopy

Answer 21

Identify molecular composition of the Phiber

Question 22

Thin layer chromatography

Answer 22

Separate the dyes extracted from the fibre

Question 23

What colour is 650nm ?

Answer 23

Red

Question 24

What nm is violet ?

Answer 24

400

Question 25

Technique of uv spectroscopy

Answer 25

Hair - identify coloursnts and dues on the hair Natural fibres - identify dyes on fibres Synthetic fibres - identify dyes on fibres

Question 26

Technique of IR spectroscopy

Answer 26

Hair - na Natural fibres - na Synthetic fibres - identify , classify the chemical nature of the fibre

Question 27

Technique of thin layer chromotography

Answer 27

Hair, natural fibres, synthetic fibres - identify dyes and chemical treatments

Question 28

Technique of neutron activation analysis

Answer 28

Hair - identify and quantify trace elements in hair Natural fibres - na Synthetic fibres - na

Question 29

What is glass ?

Answer 29

A amorphous solid based on sand , manifactured at 1600c using silican or limestone or alumina

Question 30

How is glass classified and individualised?

Answer 30

``` Flatness Optical prowprties Density Refractive index Analyse of trave elements ```

Question 31

Float glass will fluoresce under how much uv ?

Answer 31

254nm

Question 32

How to determine glass density ?

Answer 32

Suspending fragments in liqudi of known density

Question 33

What 2 ways to analyse for trace metals in glass ?

Answer 33

Optical emission | Or x-ray fluorescence soectroscopy

Question 34

What year was the glass case in new zealand ?

Answer 34

1991

Question 35

Pharmacy was robbed , the suspects clothes were analysed to find what?

Answer 35

11 glass fragments and small flakes of yellow paint were found on suspect A 3 fragments and more yellow paint chils found on B

Question 36

Glass was examined and this showed ?

Answer 36

Flat glass urgaves and uv fluorescence showed fragmenrs were plate glass

Question 37

What was concluded ?

Answer 37

Glass evidence supported paint chips

Question 38

What are paint chils formulaed oht of ?

Answer 38

Binder, pigment and solvent

Question 39

Whats the key component of paint chips?

Answer 39

Pigemnt

Question 40

How are paint chips examined ?

Answer 40

Microscopy , colour looked at via Microspectrophotometry Chemical charcetristics - ir spectroscopy Organic compoents - purolysis gad chromotography