Decontaminating Investigation Equipment: Clearing Traces of Ignitable Liquids

During a recent court case, the following question was asked by the defendant’s attorney. “What method of decontaminating your fire investigations equipment was used to prevent cross contamination of the scene?” As you can imagine, this doesn’t...


During a recent court case, the following question was asked by the defendant’s attorney. “What method of decontaminating your fire investigations equipment was used to prevent cross contamination of the scene?” As you can imagine, this doesn’t usually turn out great for the prosecution in any case. With one sentence, the private investigator for the insurance company raised enough doubt in the jury’s eyes to sway the jury to a not guilty verdict when the investigator said, “I haven’t washed my bunker boots in 20 years!”

Taking the loss of this case and wanting to prevent others like it, investigators with the City of Thornton (CO) Fire Department found a need to have a written guideline to be followed by all of our department personnel. A guideline to decontaminate as much equipment as possible, and prevent cross contamination of the scene and evidence collected on future incidents.

After calling other investigators in the Denver Metropolitan area, as well as checking the Internet in an effort to see what other departments use for decontaminating equipment, I was unable to come up with any guidelines or procedures. With the lack of information in the investigations community, I decided to conduct a “decontamination experiment.”

With the assistance of Colorado Bureau of Investigations agent Jerry Means and his partner, accelerant detection canine Sadie, the experiment was conducted testing three commonly used multi-purpose cleaners and degreasers: Greased Lightning, manufactured by HomeCare Labs; Simple Green, manufactured by Sunshine Makers, Inc.; and Formula 409, manufactured by Clorox Professional Products Company.

We had four two-gallon plastic buckets with lids, and purchased the aforementioned cleaning products plus three each of the following: two-inch pure bristle paint brushes with wooden handles, two-inch concrete/masonry trowels with hard plastic handles, plastic putty knife, wooden paint stirring sticks, leather and canvas work gloves, a two-inch by four-inch piece of rubber from an inner-tube (similar to the rubber of rubber bunker or day boots), and an eight-inch by eight-inch piece of denim from a pair jeans.

To make sure each item to be used during the testing was not already contaminated, Agent Means and K9 Sadie conducted a “sniff” of all items. The items were placed throughout the fire station in an area that no accelerant or ignitable liquid should be found – bedrooms, office, television room and a hallway.

Once Agent Means and K9 Sadie determined all items to be tested were free of ignitable liquids, a two-gallon bucket was filled halfway with absorbent, and then eight ounces of gasoline was added to the absorbent. This mixture was used to simulate ignitable liquid-laced ash that could be found at the scene of a structure fire. The lid was then placed on the bucket, and the absorbent and gasoline mix was shaken to ensure adequate dispersion of the gasoline in the absorbent.

After the fuel/absorbent mixture was prepared, all of the items to be tested were placed in the fuel/absorbent bucket, the lid placed back on, and the bucket was shaken so the fuel/absorbent could be transferred to each item. While this was occurring, Agent Means and K9 Sadie completed a “sniff” of the apparatus bay at the fire station to ensure no ignitable liquids were present, which could lead to false positives during the next phase of testing. As hard as it is to believe, the fire station apparatus bay was actually found to be clean!

All items to be tested were removed from the fuel/absorbent mixture bucket, one at a time, and placed throughout the apparatus bay. To eliminate the possibility of cross contamination, clean nitrile gloves were used with each item as it was removed from the bucket and placed on the floor. Agent Means and K9 Sadie then conducted another “sniff” and determined all items to be tested did in fact test positive for ignitable liquids.

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