Broken, torn, or cut materials can be matched back together directly and/or indirectly. Direct physical matches are when two pieces of a material are physically fit back together using pattern of the broken edges and surface features. Indirect physical matches occur when two pieces of a material are matched together using surface features such as scratches or extrusion marks. A physical fit or an abundance of matching surface features is sufficient to establish identity between two pieces. A physical match may be established within many types of materials. Possible types of evidence include tape, plastic, metal,
glass, paint, wood, matches, and plastic bags.
We most often get requests for physical match exams in:
- Hit and Run
Some examples of things we can physically match back together are:
- Glass- Glass at the scene and the suspect’s clothing
- Automotive parts- Parts left at the scene and the suspect’s car
- Tape- Tape used to bind a victim and the roll of tape
- Weapons- Piece of a knife blade left at scene and the knife from a suspect
Collection and Packaging of Physical Match
Note: For all items of evidence, consider other types of testing such as latent print, DNA, arson, firearm, and other types of trace exams when packaging and submitting evidence.
- Wrap the pieces in tissue paper to protect the damaged areas from becoming altered.
- Lay the sticky side of tape on to clear acetate to prevent further balling and place in box.
- If the piece of evidence is large, use paper or cardboard to protect the area from which the piece may have come from.