Criminalists in Forensic Arson Analysis have, at a minimum a B.S. degree in chemistry or other closely related physical science which includes 20 to 30 semester hours of chemistry in its curriculum. These highly trained experts use gas chromatographic techniques to detect the presence or absence of an accelerant in fire debris samples which were collected by an Arson Investigator.  Some agencies use specially trained canines to ‘sniff’ out possible accelerant(s) at an arson event.  The positive identification, by use of gas chromatography, of the presence of an accelerant when there isn’t a justification of its presence would be indicative of an arson event.

INTRODUCTION 

 Many petroleum products and other flammable fluids are the most common types of liquids used to accelerate a fire.  Alcohols, gasoline, stove oil, paint thinners, solvents and other fuels are examples of ignitable liquids found in fire debris. Identifiable residues can be recovered and collected at many suspicious fire scenes. The evidence is then processed and a sample is collected for gas chromatography analysis.  The identification and/or classification of flammable accelerants is made  using state of the art instrumentation to identify ignitable liquids that usually indicates the fire was intentionally set.

EVIDENCE COLLECTION

The SLED Arson Laboratory receives evidence from various Fire Departments, Police Departments, Sheriff's Offices, members of the SLED Arson Control Team,  Bureau of Alcohol, Tobacco and Firearms, and other law enforcement agencies.

EVIDENCE RECEIVED

All Arson evidence received by the Forensic Laboratory Evidence Login Department is assigned a Laboratory File Number and is sealed with evidence tape. It is then transferred to the Arson Lab evidence storage area. The samples are analyzed utilizing Gas Chromatograph and Gas Chromatograph/Mass Spectrometer to identify ignitable liquids.

EVIDENCE ANALYZED

Samples are processed using various extraction techniques such as Purge and Trap, Adsorption/Elution, Dynamic Headspace, and other methods.  Liquid samples are collected and prepared for instrumental analysis.

INSTRUMENTATION – GAS CHROMATOGRAPH

In arson debris analysis the Gas Chromatograph (GC) is able to separate the components of petroleum products into reproducible patterns.  These patterns can be used to compare unknown samples to known standards analyzed on the same GC using the same methods.  This is a presumptive test. 

GAS CHROMATOGRAPH – MASS SPECTROMETER

The GC separates mixtures into pure components and the Mass Spectrometer components are

 ionized and fragmented into reproducible patterns.  These patterns are called spectra and are unique as fingerprints.  The spectra searched against a database of 130,000 compounds the best matches are shown on computer screen.  Once a Forensic Scientist visually confirms, then the identification of compound becomes a confirmatory test. 

COURT TESTIMONY

Expert witness testimony may be given in  magistrates, state, and/or federal courts.