FORS-2107EL Lecture Notes - Lecture 15: Birefringence, Cuticle, Nylon
27 Jun 2018
School
Department
Course
Professor
Forensic Science - Day 15 2018.03.15.
Hair and Fibres Analysis
-Fibres, hairs, and other trace evidence can be transferred between people, and
between people and objects, with each contact event (Locard’s Principle and Trace
Evidence)
-We are always trying to associate a known sample vs a questioned sample
-Hair and fibre evidence provides Investigative aid, by providing associative
information with respect to a known and questioned fibre or hair sample
-Process of hair and fibre analysis:
-Collection of trace evidence
-Screening: hair and/or fibre identification
-Comparison: known hair/fibre vs questioned hair/fibre
-Textile damage assesment
-Questions of interest
-Can we estimate ethnicity based on hair
-Can we collect DNA from hair
-Can we distinguish animal hair from human hair
-Can we conclusively establish contact between individuals based on hair/fibre
analysis
Collection
-The collection process should be efficient - comprehensive collection of extraneous
hair and fibres
-The collection process must prevent/minimize the potential for contamination of items
between each other or from the external environment
-Proper storage of items for further examination
-Collections are normally done with tape, and sometimes can be picked up with
tweezers (in microscopic examination)
Evidence Handling
-Items are separated in to group that originate from common source, therefore 2
things being analyzed will not be touching each other so not accidental transfer
occurs
-Sequence is chosen for taping items from different sources in order to minimize inter
item contamination
-Items from different sources are taped in different rooms
-The examiner’s clothes are taped for control purposes as well
-A different lab coat is worn for taping items from different sources
-Tape stored in plastic bags with case # / item # added, such that there is minimal
chance of contamination between tape/items
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Fibres, hairs, and other trace evidence can be transferred between people, and between people and objects, with each contact event (locard"s principle and trace. We are always trying to associate a known sample vs a questioned sample. Hair and bre evidence provides investigative aid, by providing associative information with respect to a known and questioned bre or hair sample. Can we estimate ethnicity based on hair. Can we distinguish animal hair from human hair. Can we conclusively establish contact between individuals based on hair/ bre analysis. The collection process should be ef cient - comprehensive collection of extraneous hair and bres. The collection process must prevent/minimize the potential for contamination of items between each other or from the external environment. Proper storage of items for further examination. Collections are normally done with tape, and sometimes can be picked up with tweezers (in microscopic examination)
