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
deliberately set fires,
most accelerants are ignitable liquids. The most common ignitable liquid
used as an accelerant is gasoline. The BFFEA determines the presence and
identity of ignitable liquids. Whether or not they were used as
"accelerants" is for the investigator or the courts to determine.
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 liquid molecules. After being extracted from the
evidence sample, the trapped ignitable liquid molecules are put into a liquid
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 and
mass spectra 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 should see a mixed
pattern and should 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 volatile residues or 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. BFFEA strongly suggests limiting their use to items with odd
shapes or bulk that will not fit into a gallon can. If the debris
placed inside them has sharp points or edges, the plastic bag could be
punctured. Plastic bags must be completely heat sealed. 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 link to "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 of fire debris 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 prepare 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 was contaminated. This test is done by submitting
an unused portion of the absorbent material as a separate comparison sample.
Comparison samples of any absorbents used to collect a sample should be
taken at a different location as ignitable liquid vapors may be absorbed
from the air near the scene.
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 incident it should have rush priority.
2. Injured victims or responders. If there are burn victims or first
responders who were injured in any phase of the incident (fire suppression,
scene investigation, or scene 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 may be 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 costs for work performed by the Bureau as well as any costs
associated with bringing Bureau personnel to their courts for testimony.
Q: Where can I learn more about the schools that offer
degrees in forensics?
A: The following websites list several of the schools and information
although there are additional resources if you search the web:
http://aafs.org/accredited
http://www.ncjrs.gov/pdffiles1/nij/203099.pdf
http://forensicsciencetechnician.net
Q: Who do I contact if I need further information?
A: Call Bureau Chief Carl Chasteen at 850/539-2705 or e-mail
Carl Chasteen.
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