Julia A. Dolan
Speaker: Julia A. Dolan, Bureau of Alcohol, Tobacco and Firearms, Rockville, MD 20850
Topic: Applications of Mass Spectrometry to Forensic Science: Analysis of Evidence from Arson and Explosive Incidents - Video (running time 00:45:20) *
Place: Building 549, Auditorium, NCI at Frederick, Frederick, MD
Time: Tuesday, January 14, 2003, at 2:00 PM
Abstract: Forensic Science Laboratories have historically used the most modern scientific methods available to assist investigators in determining what may have occurred during the commission of a crime. As advances in analytical capabilities have improved, forensic scientists have been able to provide more detailed and valuable information to law enforcement investigators in the field. This presentation will focus on the applications of forensic science, specifically gas chromatography-mass spectrometry, to the fields of fire and explosion investigations.
One of the main challenges for an arson investigator is often determining the origin and cause of the fire. Unlike many other criminal actions, arson may go undetected for the simple reason that a fire may be erroneously ruled accidental, when it was in fact intentionally set. One factor that may be significant in determining if a fire was intentionally set is the presence of an accelerant. An accelerant may be any agent used to initiate a fire, or increase its rate of growth or spread, and is often a flammable liquid. Fire investigators submit samples from a suspected incendiary fire scene to the laboratory in order to determine if an accelerant was used. Analytical techniques used by the laboratory include an extraction followed by GC-MS analysis. Most often, the technique of reconstructed ion chromatography (RIC) is applied because of the complexity of the generated data. An overview of how fire scene evidence is processed, and how the data is analyzed will be presented in the context of a fire investigation. Additionally, concerns regarding significance of findings will be addressed.
Forensic examination of evidence from an explosive scene includes not only the chemical analysis of explosive residues, but also examination of debris and components from the scene which can be used to aid the investigators in determining how the device was initiated. Chemical analysis of explosive residues offers unique challenges to the analyst due to the fact that explosives often are nearly entirely consumed during the explosion. Additionally, the inherent instability of explosive compounds makes traditional electron impact mass spectrometry to be fairly ineffective. To counteract these difficulties, explosive residues are most often analyzed by negative ion chemical ionization (NICI) methods. A brief overview of the chemical analysis of explosive residues will be provided, along with case examples of other evidence of interest.
Forensic science can be applied to a variety of situations, and as new analytical techniques are being developed, the forensic scientist can provide more and more information to the investigator. The partnership of the laboratory analyst with the field investigator has proven to be extremely valuable, particularly in the areas of arson and explosion investigations.
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The Mass Spectrometry Interest Group of the Frederick National Laboratory for Cancer Research (1999-2013)
The Frederick National Laboratory for Cancer Research (Frederick, MD 21702 USA)