Division of State Fire Marshal

Bureau of Forensic Fire and Explosives Analysis

Frequently Asked Questions

Q: What is an accelerant?
A: An accelerant is technically anything which speeds up a process. In arson, most accelerants are ignitable liquids. The most common ignitable liquid used as an accelerant is gasoline.

Q: How do you find ignitable liquids?
A: Fire scene investigators utilize their skills and tools (electronic sniffers and specially trained canines) in the fire scene to find areas with a high probability of the presence of an ignitable liquid. They collect one or more samples and place them in vapor tight containers. These are sent to the laboratory. The technicians and analysts in the Bureau subject the evidence to a technique called "passive headspace concentration" in order to extract trapped ignitable liquids and make a solution. The solution (extract) is then injected into a gas chromatograph with mass spectral detector. This instrument creates an electronic representation of the organic chemicals in the sample mixture. The complexity of this mixture is represented as a "total ion chromatogram" which can then be further subdivided into specific ion fragment profiles to determine the presence or absence of characteristics specific to ignitable liquids.

Q: What if somebody mixes several ignitable liquids together?
A: Ignitable liquids can be divided into several classes based on the presence or absence of specific chemical compounds. Familiarity with these classes allows the analyst to distinguish between a medium petroleum distillate and deteriorated gasoline. If a mixture were used the analyst would see a mixed pattern and would be able to make a differentiation.

Q: How should evidence from a fire scene be preserved and packaged?
A: Evidence from fire scenes should be packaged so that the sample is protected from both evaporation of ignitable liquid residues and contamination of the residues after they are collected. This is best accomplished by placing the sample in an air-tight container. The most common are clean unused paint cans with a friction lid which is tightly sealed. Glass jars with tight fitting screw-on lids (using a Teflon type liner) may also be used. If glass jars are used, take care that they will not break during transport or shipment. Some brands of nylon "arson" plastic evidence bags are on the market. Some studies show them to be very useful so long as they are sealed properly. If the debris placed inside them has sharp points or edges, the bag could be punctured. Regardless of the type of container used, place the debris in it without drying as this will reduce the presence of the ignitable liquid traces. The container should never be filled more than fifty (50%) to seventy-five (75%) percent full, as the laboratory needs an adequate vapor space above the debris for testing. Please see the "Guidelines for Submission" on the Bureau Main Page.

Q: What are the key exceptions or differences if I have evidence from explosions or clandestine labs?
A: The Bureau will not accept any intact explosive devises. They must be rendered "safe", or disassembled before submission. For items from a clandestine laboratory, if there is a suspicion that any drugs are present, the item must be submitted to the Florida Department of Law Enforcement (FDLE) as the Bureau will not accept any drugs for analysis. Items other than fire debris or organic based solvents should not be directly placed into a metal container as the item may chemically react with the metal. Instead, glass or plastic containers should be used. Be careful to observe if there is a chemical reaction or gas evolution inside the container as this may cause a build-up of pressure in the container to the point where it would burst. Additionally, these types of evidence may require larger sampling amounts to ensure an adequate variety of tests. Please call the Bureau if in doubt.

Q: What can I (the investigator) do to make sure the best sample is sent to the lab?
A: First, take care in selecting the sample to be tested. It is best to take a sample from the area of origin between the center and the edge of a pattern suspected of containing an ignitable liquid. Second, send the sample to the laboratory as soon as possible. Deterioration of ignitable liquids occurs whenever they are not sealed in air-tight containers. Additionally, certain microbes have been known to "eat" components of ignitable liquids. If the concentration of ignitable liquid is low and the presence of microbes high (as in soil samples), a delay in sending the sample may cause enough of a change in an ignitable liquid so that the analyst cannot make a clear determination. Third, if at all possible, send in a "comparison" sample. This would be a sample (preferably un-burned) of the same type of material as in the debris to be tested. For example, if the sample from the point of origin is burned carpet and padding, a sample of the same type of carpet and padding from a protected area (under a bookcase or planter) would be a good "comparison sample." The laboratory will burn the "comparison" sample under controlled conditions so that the potential interferences can be seen.  Comparison samples are also any absorbents used to collect a sample. A paper towel, gauze pad, or hydrophobic pad used to absorb a liquid should be tested to determine it is was contaminated. This test is done by submitting an unused portion of the absorbent material as a separate comparison sample.

Q: How long will it take to get results?
A: Ninety-five percent of the samples submitted to the Bureau are completed and a report issued in fewer than 10 calendar days. Certain cases, depending on the number of samples and the difficulty in interpreting the results, can be completed in two to three days. These RUSH cases need to meet certain criteria:

1. Fatality - If a fatality occurred in the fire it should have rush priority.

2. Injured victims or firefighters. If there are burn victims or firefighters who were injured in any phase of the fire (suppression, investigation, or clean-up) it should be marked as rush.

3. Major fires or explosions with significant dollar losses. If a city block, a large business, or historical site should burn or be involved with an explosion it should be marked rush.

4. Suspect in custody/impending court would also be a rush criteria.

Q: Who can submit samples?
A: At this time, the Division of State Fire Marshal's Bureau of Forensic Fire and Explosives Analysis will accept samples from any government/public service agency in Florida. This includes all police or fire investigation agencies for the state, county, or municipality. This, also, includes investigators from State's Attorney Offices or from the Public Defender's Offices. Other State of Florida or federal agencies investigating incidents occurring in Florida may submit evidence, but should contact the Bureau in advance. In the spirit of forensic cooperation, foreign law enforcement or fire investigation agencies have been permitted to submit evidence under specific instances and with prior approval.

Q: What does an analysis of the evidence cost the submitting agency?
A: At present, the only cost to the submitting agency is the cost of shipping the evidence to the laboratory. The Bureau does not charge for analysis of samples. We do charge reasonable and customary fees for the reproduction of reports, case files, and photographs/images. Foreign submitters must also agree to bear all shipping costs to and from the Bureau as well as any costs associated with bringing Bureau personnel to their courts for testimony.

Q: Who do I contact if I need further information?
A: Call Carl Chasteen at 850/539-2700 or e-mail Carl Chasteen.

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