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FY YEAR: CSI > 11. Trace Evidence Analysis > Flashcards

11. Trace Evidence Analysis Flashcards

1
Q

What is trace evidence ?

Name some examples

A

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

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2
Q

Whats inceptive search ?

A

Extract distinctive material

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3
Q

Whats reactive search ?

A

Looking out for particular material based on other information

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4
Q

Name some recovery methods

A 
Shaking
Swabbing
Vacuuming 
Tape-lifting 
Brushing
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5
Q

What is naturally shed hair called ?

A

Telegen

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6
Q

What is torn out hair called ?

A

Anagen

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7
Q

What is hair comprised on ?

A

Keratin

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8
Q

What are the racial origins of hair ?

A

Caucasoid
Mongoloid
Negroid

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9
Q

Whats the structure of hair ?

A

Outside - cuticle
Inside - cortex

Medulla
Cortical fusi
Pigment granule

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10
Q

Whats a fibre ?

A

Smallest unit of a textile which has been spun into thread

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11
Q

Why can fibre evidence be individualised ?

A

Because of the variety of physical and chemical characteristics

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12
Q

What are natural fibres ?

A 
Animal fibres ( silk, wool, hair ) vegtable fibres ( linen, cotton, jute, kapok, coir )
mineral fibres ( asbestos )
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13
Q

What are organic fibres ?

A

Synthetic polymers - polyethene,polyamide,polyester

Natural polymers -
Cellulose, materials, rubber

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14
Q

What are inorganic fibres ?

A

Carbon, ceramic, glass, metal

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15
Q

How to compare fibres ?

A

Establish points of identity

Avoud contamination

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16
Q

What can a compound microscrope see from fibres ?

A 
Diamater
Shape
Surface features
Colour
Refractive index
Burefringence - determinning chemical nature
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17
Q

Stereo microscope

A

Low magnification

Hairs - classify individualise

Natural fibres - identify classify, finres appearance and distribution

Sumthetic fibres - indentify classfiy fibres appearance and distribution

18
Q

Compoun/polarised microscopy

A

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
Q

Comparison microcscapy

A

Manification ranges

Hair - comapre questioned and knows fibres

20
Q

UV visible microspectrophotometry

A

Characterises colour of the fibre

21
Q

Infared microspectroscopy

A

Identify molecular composition of the Phiber

22
Q

Thin layer chromatography

A

Separate the dyes extracted from the fibre

23
Q

What colour is 650nm ?

A

Red

24
Q

What nm is violet ?

A

400

25
Q

Technique of uv spectroscopy

A

Hair - identify coloursnts and dues on the hair

Natural fibres - identify dyes on fibres

Synthetic fibres - identify dyes on fibres

26
Q

Technique of IR spectroscopy

A

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

27
Q

Technique of thin layer chromotography

A

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

28
Q

Technique of neutron activation analysis

A

Hair - identify and quantify trace elements in hair

Natural fibres - na
Synthetic fibres - na

29
Q

What is glass ?

A

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

30
Q

How is glass classified and individualised?

A 
Flatness 
Optical prowprties
Density
Refractive index 
Analyse of trave elements
31
Q

Float glass will fluoresce under how much uv ?

A

254nm

32
Q

How to determine glass density ?

A

Suspending fragments in liqudi of known density

33
Q

What 2 ways to analyse for trace metals in glass ?

A

Optical emission

Or x-ray fluorescence soectroscopy

34
Q

What year was the glass case in new zealand ?

A

1991

35
Q

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

A

11 glass fragments and small flakes of yellow paint were found on suspect A

3 fragments and more yellow paint chils found on B

36
Q

Glass was examined and this showed ?

A

Flat glass urgaves and uv fluorescence showed fragmenrs were plate glass

37
Q

What was concluded ?

A

Glass evidence supported paint chips

38
Q

What are paint chils formulaed oht of ?

A

Binder, pigment and solvent

39
Q

Whats the key component of paint chips?

A

Pigemnt

40
Q

How are paint chips examined ?

A

Microscopy , colour looked at via Microspectrophotometry
Chemical charcetristics - ir spectroscopy

Organic compoents - purolysis gad chromotography

FY YEAR: CSI (7 decks)

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