PHYSICAL EVIDENCE MANUAL - Crime Scene Investigator Network

Physical Evidence Manual
Adopted: May 2002
Revisions: 6
Last Revision: January 31, 2008
12.0 IMPRESSION EVIDENCE
Shoe, tire and fabric impressions are routinely present at crime scenes and are
frequently overlooked by law enforcement personnel. In many instances the
examination of these impressions can provide the investigator with valuable
leads such as the type, make/model, and approximate size of the footwear or
tire. If properly documented and collected, almost every impression left by a shoe
or tire has value for forensic comparison to a suspected source. Even when
suspect footwear is not available, images of impressions from scenes may be
submitted to the laboratory for search in the SICAR (Shoeprint Image Capture
and Retrieval) database for make/model determination and comparison to
impressions from other scenes.
Impression Evidence General Guidelines
• Photograph the impression with and without a scale device. The scale
should be a two dimensional ruler.
• Whenever possible, retrieve the original item containing the impression
(e.g. paper, glass, flooring, door) for submission to the laboratory.
• Lift or cast the impression when it is in soil, sand, or snow, or when it
cannot be sent to the laboratory.
Photographic Methods
• Photographs of the evidence should always be taken first before any
attempt to collect it.
• Photograph the general scene that contains the impression evidence.
• Digital photography is acceptable; however, low resolution images may be
of limited use in comparisons. If using a film camera, select a camera with
a large negative format such as 35mm or 4x5 inch. Fine grain black and
white or color film (ISO 125 or less) is preferred.
• Place the camera on a tripod with the camera directly over and
perpendicular to the impression. It is important to avoid taking the photos
at an angle to the impression. This can result in the inability to accurately
enlarge the images as needed for comparison.
• Adjust the camera height so the impression and scale fill the frame.
• Use overlapping exposures to record elongated impressions.
• Use side lighting at various angles and from various directions to
illuminate tread design more clearly. This may require shading the camera
setup from high, bright sunlight with a makeshift tent and access to a
detachable flash unit.
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