Criminalistics Laboratory - Trace Evidence Section

Tire pieces matching

The Trace Evidence Section of the DCI Crime Laboratory examines a wide variety of materials, from crime scenes, submitted as evidence. In the course of committing a crime, small amounts of material may be transferred from one surface to another. Being able to establish a source for the transferred material may help connect the individuals involved to the crime scene. The Trace Evidence Section is set up for comparing the physical and chemical properties of questioned samples to the known samples and the identification of unknown materials.

 

The following is a list of the types of materials that can be encountered in a transfer of evidence and their possible sources:

  • Fibers - clothing, carpet, upholstery

  • Paint - vehicle, architectural, tools

  • Glass - vehicle, architectural, container

  • Soil - any source

  • Safe Insulation

  • Lubricants - petroleum and water based

  • Adhesives - tapes, glue

  • Plastics - vehicle trim, numerous other sources

  • Low explosives

Pipe bomb from mailbox
                                                               Pipe bomb from mailbox

 

Lamp filament examination for on or off at the time of impact
                                  Lamp filament examination for on or off at the time of impact

 

Mineral grain from soil sample
                                                            Mineral grain from soil sample

 

 

Other examinations performed in the Trace Evidence Section:

  • Speedometer needle slap for determination of speed at the time of impact

  • Light bulb filaments to determine if "on" or "off" at the time of breakage

  • Duct tape comparisons

  • Determination of whether a match came from a particular matchbook

  • Rope and cordage comparisons

  • Identification of unknown powders and liquids