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Fibers
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Published on Nov 29, 2015
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PRESENTATION OUTLINE
1.
FIBER ANALYSIS
BY: JESSICA HOGLE
Photo by
Thomas Tolkien
2.
FIBER EVIDENCE
Fibers left (in most cases) when there is human to human contact
Hope to trace to offender
Class evidence (can't direct back to one person)
Other factors need to be involved to convict
3.
HOW TO COLLECT
collect using tweezers, tape, or a vacuum
Usually from carpet, furniture, blankets, ect
4.
NATURAL OR SYNTHETIC
First determine if natural or synthetic
Natural: plants (cotton) or animals (sheep)
Synthetic: man made (rayon, acetate, polyester)
5.
COMPOUND MICROSCOPE
Uses reflected light
Magnified through series of lenses
6.
COMPARISON MICROSCOPE
Two compound microscopes
Joined by optical bridge
Used for precise identification
7.
SPECTOMETER
Separate light into component wavelengths
Resulting lines=absorption lines
Measures light intensity
8.
MICROSPECTROPHOTOMETER
Locates minute traces
Shows how light interacts with material
Link to computerized spectrophotometer for more accuracy
Increases number of identifying characteristics
9.
ANALYSIS
First compare color and diameter
If similar, use chromatography for further analysis
10.
CLASS EVIDENCE
Compared shape, dyes, chemical composition ect
If with all this, it's still class evidence
Same fibers can have different state of origin
jessica hogle
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