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Hair and Fibre Evidence

Forensic Science
Course Code
Joel Cahn

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Hair and Fibre Evidence
Question 2 b) what was dr. Roger`s answer to that question in a). C) how did dr. Rogers
come to that conclusion.
History of Trace Evidence
The microscopic debris that covers our bodies are the mute witnesses sure and
faithful, of all our movements and all our encounters
Every contact leaves a trace
Fibres and hairs can be transferred b/w individuals, b/w individuals and objects, or
between objects
Circle: suspect <-- complainant crime scene
Textile and Trace Evidence
Textile and fibre-trace. Fibre is a basic unit of a textile/fabric
Investigative - Associative
Collection of trace evidence
Hair identification
Fibre identification and comparison
Textile damage assessment
Transfer and Persistence
Approximately 80% of hairs/fibres are lost in the first 4 hours from contact/transfer
Factors affecting rate of loss:
oType of donor/recipient textile (ex. Wont stick to nylon which is smooth,
compared to wool which is rough, trace is held on and persisted longer)
oLength of hair/fibre (shorter ones are the one that cant be seen)
oEnvironmental conditions
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oEfficient collection of evidential extraneous hair and fibres (need to use
whatever you can get so have to be careful)
oPrevention of contamination between items or environment
oProper storage of evidence for later use (storage it without loss or
oPicking by eye or under a stereomicroscope (using forceps)
Proper Handling of Evidence
Case items are segregated into groups which originate from a common source
A sequence is chosen for taping items from different sources so that potential
contaminations in minimized
Items from different sources are taped in different H&F taping rooms by qualified
H&F personnel
A different lab coat is worn for taping items from different sources
Work area is cleaned before and after taping and mounting
Examiners clothes are taped for control purposes (just in case examiner comes in
contact and there is a transfer)
Hair and Fibre Examination
Comparison bright field and fluorescence microscopy
Polarized light microscopy, solubility, melting point determination (solubility and
M.P. determination is not used usually, because very destructive)
FTIR (preferred), microspectrophotmetry (to determine if they have same or similar
characteristics like colour), thin layer chromatography
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