Lucas, Douglas M.

CANADIAN
FORENSIC SCIENTIST

In 1960 Douglas M. Lucas was the first forensic scientist to utilize the technique of gas chromatography as a means of identification of petroleum products used as accelerants in suspected cases of arson . In so doing, he recognized the inherent difficulties in attempting to minutely identify accelerants by brand type or commercial manufacturer.

In forensic fire investigations (suspected arson, acts of terrorism, etc.) it is extremely important to analyze the explosion, blast, or fire debris for the presence of small amounts of suspected volatile accelerants, which can be used to prove that the fire or blast was caused intentionally.

Accelerants are chemical fuels that cause fires to burn at higher temperatures, to spread exceptionally rapidly, or to be extremely difficult to contain or extinguish. Accelerant residue often remains at the crime scene. If identified, the presence of an accelerant can be used as forensic legal evidence of arson. However, even when it is collected immediately after the incident, carefully packaged, promptly transported, and analyzed by the best methods, test results have not always been conclusive or perfectly accurate.

Part of the difficulty in accurate analysis is that petroleum distillates, typically used as accelerants, typically undergo physical and biochemical changes as they burn or evaporate. In addition, arsonists generally use compounds of gasoline, kerosene, or diesel fuel as accelerants. Those crude oil products are made from mixtures that may contain thousands of different organic compounds , most of which contain only carbon and hydrogen atoms (hydrocarbons).

In order to identify volatile accelerants in a forensic scientific (laboratory) setting, it is first necessary to isolate the liquid suspected of being an accelerant from the surrounding fire or blast debris. It is then analyzed using gas chromatography, which results in the production of a graph called a chromatogram. The chromatogram is then computer analyzed and compared with chromatograms of known accelerants until a match is found.

Gas chromatography is one of the most effective techniques for detecting accelerants in explosion, blast, or fire debris. The basic gas chromatography technique utilizes uses a stream of gas (nitrogen or helium) as a carrier to move a mixture of gaseous materials along a long column or tube filled with a separating compound. Gas chromatography involves separating mixtures of gases into their individual chemical components based on the different boiling points of their hydrocarbons. Each gas in the mixture can then be identified, because each produces a distinct chromatogram.

Lucas set the worldwide standard for volatile accelerant identification in forensic arson investigations; gas chromatography remains considered among the most accurate scientific means of identifying flammable or combustible accelerant residues. In addition, Lucas authored "Ethical responsibilities of the forensic scientist: exploring the limits," published in the Journal of Forensic Science in 1989.

see also Arson; Crime scene cleaning; Fire debris; Fire investigation.