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Strengthening Forensic Science in the United States: A Path Forward
mentation. The Technical Working Group for Fire and Explosives (TWGFEX), a group of fire debris and explosives examiners, suggests that an explosives examiner be required to possess a bachelor’s degree in a natural or applied science, with recommended coursework in chemistry and instrumental analysis.112 The group also recommends that the examiner complete a training program that includes the analysis of low and high explosives, instruction in the use of instrumentation used in routine analyses, the construction of explosive devices, and participation in a postblast investigation course. Although there is no official certification program for explosives examiners, TWGFEX has devised a suggested training guide. The guide is divided into seven modules, each with a reading list, practical exercises, and methods of evaluation.113 To ensure that examiners maintain a level of competency, proficiency testing (internal or external) is required by ASCLD/LAB once per calendar year.114
The ultimate goal of an explosives examination is the identification of the explosive material used, whether it is through the analysis of an intact material or of the residue left behind when the material explodes. Intact material lends itself to being more easily identified. The individual components of postblast residue may often be identified (e.g., potassium chloride and potassium sulfate). The training and experience of examiners allows them to deduce what types of explosive material were originally present from possible combinations of explosive materials.
Whether it is a low explosive or high explosive, the analysis of an intact explosive material follows a procedure that begins with a macroscopic and microscopic examination of the material, followed by a burn test, when appropriate. The results of the initial observations will dictate how the rest of the analysis will proceed. Typically it will involve the use of instrumentation that provides both elemental and structural information about the material, such as X-ray diffraction, scanning electron microscope-energy dispersive X-ray analysis, or infrared spectroscopy. TWGFEX has devised guidelines for the analysis of intact explosives that categorize the instruments that can be used based on the level of information they provide.115 The information gathered, if sufficient, can be useful in identifying the material.
The analysis of postblast explosive residues begins much like the analy-