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...


Once the items tested positive they were all collected, again using clean nitrile gloves with each item, and then separated in preparation for decontamination using the three cleaners/degreasers.

Based on the directions for use found on each container, each with different dilution recommendations or no recommendations listed at all, a ratio of one part cleaner to five parts water was prepared. All contaminated items were then rinsed with a garden hose, allowing any debris or contaminants to flow into an apparatus bay floor drain. Once all items were rinsed, they were placed into the prepared solution and were allowed to soak for 30 minutes.

Following the 30-minute soak, the items were removed and re-rinsed with the garden hose, again allowing debris and contaminants to flow into the apparatus floor drain. After the second rinse, the bucket was rinsed as well and a new batch of cleaning solution and water was prepared, again at a ratio of one part cleaner to five parts water.

Using a new scrub brush, all items tested were scrubbed in the solution and then re-rinsed a third time. Items such as the piece of rubber from the inner-tube, cement/masonry trowel, paint brush and wooden paint stirring stick were put on a clean towel and placed in the basement of the fire station to air dry for 24 hours. The canvas/leather work glove and patch of denim were taken to a washing machine and ran through a cold normal wash cycle using phosphate-free laundry soap, then allowed to air dry in the basement as well.

After the 24-hour drying period, all of the items were collected using clean nitrile gloves and placed throughout the fire station, again in the bedrooms, office, television room and hallway. Some items that were intentionally not decontaminated by using any of the three cleaners, but had been rinsed only, had been placed in the apparatus bay for testing as well.

Agent Means and K9 Sadie then conducted a “sniff” of all the items tested. Based on the “sniff” results the Greased Lightning multi-purpose cleaner and degreaser showed to be the most effective in decontaminating common fire investigations tools and clothing. Of all items tested, the piece of inner-tube rubber was the only item that could not be decontaminated by the Greased Lightning.

Formula 409 showed to be the second-most effective of the three cleaners, leaving the canvas/leather work glove and inner-tube rubber testing positive for an ignitable liquid. Simple Green showed to be the least effective of the three cleaners, leaving the canvas/leather work glove, denim patch, and inner-tube rubber testing positive for an ignitable liquid. All items that had been rinsed with water only, tested positive for an ignitable liquid, as expected.

Based on the test results the attached department standard operating guideline was written and it's attached below to download.

As past and current origin and cause determination practices come under scrutiny in the public eye, be it in written media or television, all fire department personnel, more specifically, fire investigators, need to do everything within our means to prevent cross contamination of fire scenes and our evidence. If not, we can expect to continue losing court cases because of that little legal term known as reasonable doubt.

How do you decontaminate your equipment?

BRENT BURKE is a lieutenant and fire investigator with the City of Thornton, CO, Fire Department. He has been in the fire service for 17 years, with 11 years fire-investigations experience conducting more than 200 investigations to include multiple fire-fatality incidents. Burke holds an associate of applied science degree in fire science from Red Rocks Community College, certificate of study in criminal justice from the Community College of Aurora, is a Colorado Peace Officer Standards and Training (POST) certified commissioned peace officer, and is a National Association of Fire Investigators Certified Fire and Explosion Investigator and Certified Fire Investigation Instructor.