Fiber Transfer Activity Rub your sleeve against your
Fiber Transfer Activity
Rub your sleeve against your neighbor’s sleeve. Then answer the following questions: n n Can fibers from one sleeve be detected on the other? Do hand lenses or masking tape aid the investigation? How?
Fiber Analysis
Introduction to Fibers n n n Trace evidence Class evidence Direct transfer: suspect victim Secondary transfer: source suspect victim 95% of fibers lost from crime scene within 24 hours
Forensic scientist determines: n n n n Type of fiber Color How many of each kind Textile origin Multiple Fibers Transfers Type of crime
Fiber Evidence Collected by: n Special vacuums (large areas) n Sticky tape n Forceps Tested by: n Microscopy – polarizing light, infrared n Burn test (large quantities only)
n n n Fibers are spun into yarns that have specific characteristics Yarns are woven, with different patterns, into textiles Fibers may be natural or synthetic
Fiber Classification Natural Fibers: Synthetic Fibers: (List the different types and examples of each)
Natural Fibers n Animal fibers (protein) n n n Plant fibers (cellulose) n n n Sheep – wool Goats – cashmere, mohair Rabbits – angora Caterpillar – silk Seed: cotton Fruit: coir (coconut) Stem: hemp (Cannabis), jute, flax (linen) Leaf: manila, sisal Mineral fibers n Fiberglass (glass) , asbestos (rock mineral)
WOOL COTTON FIBERGLASS
ASBESTOS FLAX JUTE
SILK HEMP
Synthetic (Man-made) Fibers n Regenerated fibers (modified natural fibers) Rayon n Celanese n Capron n n Synthetic polymer fibers Polyester n Nylon n Acrylic n Olefins n
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