Trace Evidence

The following types of evidence are analyzed by the Trace Evidence Department:

  • Gunshot Primer Residue (P-GSR)
  • Fire Debris
  • Paint
  • Fibers
  • Glass
  • Explosives
  • Bank Dye – 1-Methyaminoathroquinone (1-MAAQ)
  • Pressure Sensitive Tape
  • Physical Fit
  • General Physical and Chemical Analysis
  • Pepper Spray

Gunshot Primer Residue
Gunshot primer residue (P-GSR) analysis is performed on particle lifts collected from people suspected to have been in the vicinity of a gun when it was fired. Samples from clothing of non-victims and any other location/object (vehicle, door, etc.) where gunshot residue would have been deposited can also be analyzed. Gunshot primer residue analysis is most probative when the suspect states that he or she has not been in the vicinity of a gun when it was fired, handled a firearm, or been in contact with anything that may have gunshot residue on it, within six hours of an incident.

Fire Debris
Fire debris analysis tests for the presence of ignitable liquids. Gasoline and other petroleum products may be identified by this analysis. It is extremely important to package this evidence properly.

Typically, known paint standards are compared to unknown paint samples to determine if they share a common source. Sources of paint that can be analyzed can include vehicles, doors, windows, walls, tools, boats, bicycles, trains, safes, and mailboxes. In some cases, it may be possible to provide make, model and year ranges of vehicles involved in hit and run accidents.

Typically, known fiber standards are compared to unknown fiber samples to determine if they share a common source. Fiber evidence may link a suspect to a crime scene or to a victim. 

Glass evidence is commonly encountered in vehicular hit and runs, burglaries, homicides, and assaults. A known glass standard is compared to an unknown glass sample to determine if they have a common source. For example, a hit and run victim’s clothing may contain glass from the windshield of the suspect vehicle or a burglary suspect’s clothing or shoes may contain glass from a broken window at the crime scene.

Explosives evidence includes suspected explosive residue and exploded/unexploded devices. All devices must be rendered safe before submission to the laboratory. This evidence includes pipe bombs, chemical reaction bombs, improvised explosive devices, and pre-cursor components used to manufacture an improvised explosive device.

Bank Dye – 1-Methylaminoanthraquinone (1-MAAQ)
A special type of explosion involving bank dye packs can be analyzed for the presence of 1-Methylaminoanthraquinone (1-MAAQ).  1-MAAQ can be identified on a suspect, on their clothing, on any money recovered or on any items in the vicinity of the explosion.

Pressure Sensitive Tape
Typically, a roll of tape from a suspect is compared to unknown pieces of tape found on a victim or to pieces of tape left at a scene. Tape types that can be analyzed can include duct tape, masking tape, clear packaging tape, and electrical tape.

Physical Fit
The purpose of this examination is to physically fit evidentiary materials back together along fractured edges. This examination can be performed on any item that displays a fractured edge. Some examples are cloth, glass, paint, plastic, metal, tape, concrete and wood. When accomplished, this examination provides substantial evidence that the materials were, at one time, a single item.

General Chemical and Physical Analysis
Common types of evidence in this category include pepper sprays and unknown white powders.