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Chapter 11: Basic Skills for scene processing: Impression Evidence

Terms in this set (33)

impression evidence
tool marks, footwear or barefoot impressions, tire marks, bite marks
casting
primary mechanism of recovering impression evidence; includes both 3D and 2D marks
rubberized casting compounds, electrostatic dust lifter (ESDL), plaster and dental-stone casting, gelatin
What four primary methods of recovering impression evidence should the CSI master?
in place
the impression should be photographed __ ______
associated data like stride/gait distance and stance width
What should the CSI capture in addition to the detail of the impression with foot or shoe evidence?
silicon/rubber casting compounds and dental ston/plaster compounds
Physical casting is accomplished with what two things?
microscopic details of tool-mark impressions
Forensic casting compounds have been designed to capture what?
hard substrates (metals, wood, bone or plastic)
Rubberized casting compounds are most effective when used on what?
thoroughly mixing the base and curing catalyst
What is a critical aspect of preparation for rubber casting compounds?
ESDL (electrostatic dust lifters)
works on a simple concept: opposite charges attract; creates a more concentrated charge; not effective on wet impressions; won't hurt you (volts not amps);
dental stone
How should you cast 3D impressions?
sets harder, more forgiving, recover more detail
Why is dental stone the preferrred medium for casting?
harden the impression
what is a fixative?
on a slope, casting submerged impressions, 2D impressions
When is a form needed?
form
used in casting to contain the casting medium; typically made of expandable metal sleeves
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