Fire Scene Evidence Collection Guide
Metal fragments can be loose or embedded in an object. Transfers of metal by prying, breakage, and projectiles should be collected.
To collect metal fragments:
Photograph the fragments in place.
Wear eye protection, breathing protection, and new, unused, clean latex or nitrile gloves.
For loose fragments: Using a disposable tweezers or other appropriate tool, carefully pick up the fragment without crushing it and place it in a suitable container, such as a plastic bag, pillbox, or vial. Do not use metallic containers or metallic collection tools. If needed, wrap the fragments in clean paper to keep them from striking against each other in the container. Collect each location of metal fragments separately and package separately. DO NOT MIX PARTICLES FROM DIFFERENT AREAS.
For embedded fragments: If possible, package the entire item containing the embedded fragment. If this is not possible, cut out and package as much of the item containing the embedded fragment as possible. Allow the laboratory to remove the fragment. Collect each item separately and package separately. If the item cannot be removed, follow the procedure above for loose fragments, but instead carefully dislodge the fragment without deforming it.
If fragments are removed from victims, consult the medical examiner first, photograph completely, and note the position of the fragment on a body diagram before removal. Observe Universal Precautions and allow the fragment to air dry completely on a sheet of paper before packaging it in an air-permeable container so it does not putrefy.
Seal the container with evidence tape. Initial and date the tape.
Label the container with identifying information, including case number, date, exhibit number, a brief description, and your name.
Store the item in a secure location, such as a locked evidence van or your vehicle, until you are able to transport it to the laboratory.
Laboratory testing of metal fragments:
Metal objects may be associated through toolmark comparison. When toolmarks are not present, chemical and/or instrumental analysis can be used to compare questioned and known items. Very small pieces may only be able to be classified by element or alloy. A physical match with the parent item is also possible depending upon the size and degree of deformation of the metal fragment.
Crime Scene and Evidence Collection Handbook. Bureau of Alcohol, Tobacco, Firearms and Explosives. 2005.