Trace evidence is one of the most diverse forensic disciplines because it includes the analysis of many different materials that utilize a wide variety of laboratory techniques and analytical instrumentation.
The Trace Evidence Unit identifies and compares specific types of trace materials that may be transferred from one source to another. A particular event or a series of events between two people and/or objects may result in the transfer of these trace materials. The analysis and comparison of these materials may link a subject to a victim or a crime scene. Examples of trace materials are fibers, fabric, carpet, rope, tape and tear gas/pepper spray.
Physical match examinations may also be conducted by the Trace Evidence Unit. For example, torn pieces of fabric may be positively associated to a damaged garment or broken fragments may be reconstructed to show that they once formed part of the whole object.
Headlamps/light bulbs can be examined to determine if they were on or off at the time of an incident.
Unknown chemicals can be examined and compared to known standards to determine the identity of the substance.
Fire debris may be examined for the presence or absence of any ignitable liquids.
The Trace Evidence Unit utilizes a variety of methods and techniques to analyze items of evidence. Instrumentation used includes gas chromatography (GC), mass spectrometry (MS), infrared spectroscopy (IR), x-ray fluorescence (XRF) spectrometry and microscopy.
At this time, the Trace Evidence Unit does not have applicable instrumentation or the specific training required to perform examination on hair, wood, soil, paint or glass. These types of examinations may be sent to an outside laboratory for analysis.