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.
*TRACE EVIDENCE SECTION UPDATE MAY 2021:
Due to a retirement at the DCI Crime Laboratory, the analysis capabilities of the Trace Evidence section have been effected. At this time, the Crime Laboratory has discontinued Bulb Filament analysis (TR-B), Glass Analysis (TR-G), and Soil Analysis (TR-S). Any evidence submitted to the Crime Laboratory meeting these requests will be returned to your agency. You may be able to reach out to the FBI Laboratory for assistance with these cases. At this time, the DCI Laboratory does not anticipate bringing these capabilities back.
The retirement has also effected Paint/Polymer (TR-P) and Fiber/Textiles (TR-F) analysis. We currently do not have a trained Criminalist to perform these analysis types. It is anticipated we may have someone trained in late 2022. If you need assistance with these cases, please contact the Trace Section Supervisor at 515-725-1500 and they can assist you.
The following is a list of the types of materials that can be encountered in a transfer of evidence and their possible sources:
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Fibers - clothing, carpet, upholstery
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Paint - vehicle, architectural, tools
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Adhesives - tapes, glue
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Plastics - vehicle trim, numerous other sources
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Low explosives
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General Unknowns
Other examinations performed in the Trace Evidence Section:
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Duct tape comparisons
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Determination of whether a match came from a particular matchbook
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Rope and cordage comparisons
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Identification of unknown powders and liquids