Hair and fibre evidence Flashcards
physical evidence
Evidence that is large and visible eg. blood, broken glass
trace evidence
evidence so small you cannot see it
with the naked eye
strong evidence that a suspect has been at a crime scene.
Strands of hair or fibres from clothes, furniture and carpets
A forensic scientist compares fibres found at a crime scene, or on a
victim, with those found on
suspects’ clothes, in their homes or in their
cars.
how do foresinci scientist find out if the fibres have been cut or torn
microscope
Fabrics are made from either
natural or man-made fibres
woven together.
Some fabrics are a combination of
different fibres.
what looks different under a microscope
each type
of fibre looks different.
what can foresnic scientists discover after looking at hair samples under microscopes
forensic
scientists can tell whether the sample belongs to a human or a
different animal.
cuticle
The scaly, outer covering that is different in each animal species
what does a micrscope tell foresinc scientists about hair
thickness, coarse, colour and structure of hair
What kind of hair provides DNA that can link hairs to a suspect
Hair that has been pulled out can have skin or other substances
stuck to it.
Explain how fibres can be important evidence in the solving of a crime.
Fibres are important because they can determine if the suspect was at the scene of the crime by matching the fibres.
difference between natural fibres and synthetic fibres.
Natural fibers are the fibers which are made by using natural source materials such as plants and animals. The synthetic fibers are the ones that are made from chemical synthesis.
Describe five different tests for comparing two fibres that may be carried out in the forensic
laboratory.
optical test
microscopic test
density test
burning test
solubtilty test
types of hair fibres
acrylic fibres
nylon fibres
merino wool fibres
cotton fibres
structure of natural fibres
rougher surface, taper from root to tip and appear somewhat irregular.
structure of wool fibres
like hair hae scales
structure of synthetic fibres
smooth and even and have a much longer length (staple).
how to know if fibres come from the same source
same thickness, strength, colour, and melting point
Explain at least two ways in which a small piece of fabric found at a crime scene might be useful in solving a crime.
The print/pattern of the fabric can be compared to the suspects clothes.
If theres a whole or shape on the fabric, it identifies what garment the fabric is from.
4 types of animal fibres
-fur,
wool,
silk
cashmere
4 types of Plant fibres
cotton,
hemp,
flax
bamboo
4 types of synthetic fibres
-spandex,
polyester,
nylon
acrylic fibres
what indications does hair give
age, race and sex
