Flashcards in 11. Trace Evidence Analysis Deck (40)
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
Whats inceptive search ?
Extract distinctive material
Whats reactive search ?
Looking out for particular material based on other information
Name some recovery methods
What is naturally shed hair called ?
What is torn out hair called ?
What is hair comprised on ?
What are the racial origins of hair ?
Whats the structure of hair ?
Outside - cuticle
Inside - cortex
Whats a fibre ?
Smallest unit of a textile which has been spun into thread
Why can fibre evidence be individualised ?
Because of the variety of physical and chemical characteristics
What are natural fibres ?
Animal fibres ( silk, wool, hair ) vegtable fibres ( linen, cotton, jute, kapok, coir )
mineral fibres ( asbestos )
What are organic fibres ?
Synthetic polymers - polyethene,polyamide,polyester
Natural polymers -
Cellulose, materials, rubber
What are inorganic fibres ?
Carbon, ceramic, glass, metal
How to compare fibres ?
Establish points of identity
What can a compound microscrope see from fibres ?
Burefringence - determinning chemical nature
Hairs - classify individualise
Natural fibres - identify classify, finres appearance and distribution
Sumthetic fibres - indentify classfiy fibres appearance and distribution
Hair - classify measure identify features
Natural fibres - classify measure indentify features fluorescence
Synthetic fibres - classify and measure fuvres by optical properties, refractive index , birefringence
Hair - comapre questioned and knows fibres
UV visible microspectrophotometry
Characterises colour of the fibre
Identify molecular composition of the Phiber
Thin layer chromatography
Separate the dyes extracted from the fibre
What colour is 650nm ?
What nm is violet ?
Technique of uv spectroscopy
Hair - identify coloursnts and dues on the hair
Natural fibres - identify dyes on fibres
Synthetic fibres - identify dyes on fibres
Technique of IR spectroscopy
Hair - na
Natural fibres - na
Synthetic fibres - identify , classify the chemical nature of the fibre
Technique of thin layer chromotography
Hair, natural fibres, synthetic fibres - identify dyes and chemical treatments
Technique of neutron activation analysis
Hair - identify and quantify trace elements in hair
Natural fibres - na
Synthetic fibres - na
What is glass ?
A amorphous solid based on sand , manifactured at 1600c using silican or limestone or alumina