PHYSICAL EVIDENCE MANUAL - Crime Scene Investigator Network

Physical Evidence Manual
18.0 PLASTIC AND TAPE EVIDENCE
Plastics are composed of polymers that are manufactured into a variety of
different objects. Plastic evidence that may be encountered includes broken
vehicle reflectors, smears on clothing, and small pieces of plastic from tapes and
garbage bags.
Laboratory examination may be able to determine the type of plastic and whether
or not it is similar to a suspected source. For large, rigid plastic pieces (e.g.
broken reflectors), the laboratory can attempt a physical match.
Plastic fusion marks might be present on an individual’s clothing as a result of a
high-energy impact with a plastic component of a vehicle interior. Because a
variety of different plastics may be present on the interior of the same vehicle, it
may be possible to establish the position of the individual within the vehicle by
comparing the plastic fusion mark to standards from the vehicle interior.
Remember that a high-energy impact can cause a plastic component in a vehicle
interior to have fibers or a fabric impression from the clothing, as well.
Collection of Plastic Evidence
Large, rigid plastic pieces may be collected and packaged into paper envelopes
or bags, plastic bags, or cardboard boxes.
Small pieces of pliable plastic evidence (e.g. tape pieces, piece of garbage bag,
etc.) should be placed into a paper envelope. Tape pieces that are adhesive
should be affixed to a clear plastic sheet, not to a piece of paper, prior to
packaging.
Clothing with possible plastic fusion marks should be packaged separately into
paper bags.
Figure 11: Physical match of duct tape pieces. The piece on the right
Adopted: May was 2002 recovered from the suspect’s possession; the pieces on the left
Revisions: 6 were recovered from the crime scene.
Last Revision: January 31, 2008
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