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Chemical Unknown Analysis

The analysis of chemical unknowns involves the examination of non-narcotic materials. This type of evidence can be encountered at a variety of crime scenes, including burglaries, homicides, vandalism, and assaults. Evidence may be in the form of a solid, liquid, mixture, or gas. Submissions may be for identification and/or comparison to a known sample.

Common materials encountered by the trace section include pepper sprays and tear gas, bank dyes, acids, bases, and bleach. Other materials that have been analyzed include fire extinguisher residues, cleansers, various organic liquids, and unknown white powders used in hoax devices or as threats. 

Bear Deterrent



An example of a powerful pepper spray used in an assault and robbery, which eventually lead to a shooting. The chemical components of this spray were found both at the scene and on one of the suspect’s clothes.








Bottle Bomb


An expended chemical reaction bomb. While intended as harmless pranks, some of the chemicals used in these devices can cause serious burns, while the pressure from the gas can be sufficient to cause property damage and bodily harm.








An unknown white powder and liquid in an unmarked bottle. This bottle was taken from a protester at a demonstration. The substance was identified as antacid suspended in water – a recipe circulated on the internet as a counteragent for tear gas.







Dye Pack Pants


The inside of a pocket in a pair of sweatpants worn by a bank robbery suspect. The stains were from an exploding dye pack, and the hole was burned through the fabric when the pack went off.




  Sodium Nitrate




An unknown white powder found at a crime scene – material was determined to be sodium nitrate.