Characteristics of Shoeprints
Accidental, or identifying, characteristics are defined as "characteristics that result when something is randomly added to or taken away from a shoe outsole that either causes or contributes to making that show outsole unique." Contact with various walking surfaces or sharp objects will leave distinctive features on the surface of the outer sole. These can include cuts, scratches, patching materials, or rocks wedged in the outsole, for example.
Photography and castings capture the characteristics. The accidental characteristics are revealed through image analysis and comparison of the shoe print impression and the tread of the shoe. They serve as a "fingerprint" of the shoe, making it unique. The more identifying characteristics present on the impression of a shoe outsole that can be matched to a suspectís shoe, the stronger the weight of the evidence.
For other techniques used in Forensic Files, click here.