There are many protocols and handbooks that officers must adhere to when arriving on the scene. They must take great precautions in protecting possible evidence from being contaminated. Physical evidence must be documented and collected. The focus of this web site will be the imprint evidence that is left at many crime scenes. Physical evidence is also known as material objects.
Demonstrative evidence is classified as a model or reproduction of the real thing.
It is what can link or associate an alleged perpetrator with the scene of the crime by matching his shoe with a shoeprint left at the crime scene. Impression or imprint evidence can be three dimensional or two dimensional. A mark on a soft surface will change the structure of that surface. Three dimensional imprints are caused when an object such as a tire, shoe, or tool presses into something softer that retains the impression of that object. On a hard surface, the mark is more of an imprint leaving possible residues behind.