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Flashcards in 11. Trace Evidence Analysis Deck (40)
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1

What is trace evidence ?
Name some examples

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

2

Whats inceptive search ?

Extract distinctive material

3

Whats reactive search ?

Looking out for particular material based on other information

4

Name some recovery methods

Shaking
Swabbing
Vacuuming
Tape-lifting
Brushing

5

What is naturally shed hair called ?

Telegen

6

What is torn out hair called ?

Anagen

7

What is hair comprised on ?

Keratin

8

What are the racial origins of hair ?

Caucasoid
Mongoloid
Negroid

9

Whats the structure of hair ?

Outside - cuticle
Inside - cortex

Medulla
Cortical fusi
Pigment granule

10

Whats a fibre ?

Smallest unit of a textile which has been spun into thread

11

Why can fibre evidence be individualised ?

Because of the variety of physical and chemical characteristics

12

What are natural fibres ?

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

13

What are organic fibres ?

Synthetic polymers - polyethene,polyamide,polyester

Natural polymers -
Cellulose, materials, rubber

14

What are inorganic fibres ?

Carbon, ceramic, glass, metal

15

How to compare fibres ?

Establish points of identity
Avoud contamination

16

What can a compound microscrope see from fibres ?

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

17

Stereo microscope

Low magnification

Hairs - classify individualise

Natural fibres - identify classify, finres appearance and distribution

Sumthetic fibres - indentify classfiy fibres appearance and distribution

18

Compoun/polarised microscopy

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

19

Comparison microcscapy

Manification ranges

Hair - comapre questioned and knows fibres

20

UV visible microspectrophotometry

Characterises colour of the fibre

21

Infared microspectroscopy

Identify molecular composition of the Phiber

22

Thin layer chromatography

Separate the dyes extracted from the fibre

23

What colour is 650nm ?

Red

24

What nm is violet ?

400

25

Technique of uv spectroscopy

Hair - identify coloursnts and dues on the hair

Natural fibres - identify dyes on fibres

Synthetic fibres - identify dyes on fibres

26

Technique of IR spectroscopy

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

27

Technique of thin layer chromotography

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

28

Technique of neutron activation analysis

Hair - identify and quantify trace elements in hair

Natural fibres - na
Synthetic fibres - na

29

What is glass ?

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

30

How is glass classified and individualised?

Flatness
Optical prowprties
Density
Refractive index
Analyse of trave elements