Directed Research Project
Before an IED is sent to a laboratory for analysis, it needs to be rendered safe if it did not already initiate. Render safe procedures (RSPs) include utilizing a percussion-actuated non-electric (PAN) disrupter or a mineral water bottle disrupter. Each disrupter utilizes explosives to render the device safe by breaking open the container or disrupting the fuzing system. However, the same explosives used in the RSP are also used by criminals in IED construction. As such, the explosives used in the RSP can cause problems with the interpretation of the results from forensic analysis of the IED fragments. Compounds of analytical interest in residue include nitroglycerin (NG), diphenylamine (DPA), ethyl centralite (EC), methyl centralite (MC), and pentaerythritol tetranitrate (PETN). Instrumentation used in the analysis of the residues included a gas chromatograph/mass spectrometer (GC/MS), a liquid chromatograph/mass spectrometer (LC/MS), and a gas chromatograph with an electron capture detector (GC/ECD).
The PAN disrupter smokeless powder contained NG, DPA, and EC while the bulk detonation cord contained PETN. Only DPA decomposed after being burned. No residue was detected on the PVC pipes while residue was detected on the steel pipes and backpack mock IEDs. Overall, finding such residue in casework should not rule out the possibility that an individual used a particular explosive in the construction of the IED, but examiners should be aware of residues left by disrupters especially if the device initiates during the RSP.
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VCU Master of Science in Forensic Science Directed Research Projects
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