FAQs
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What kind of results should I expect from explosives evidence analysis?
During the analysis, scientists will confirm the type of explosion that occurred, and identify the type of explosive material and any explosive precursors such as diesel fuel or ammonium nitrate used in fertilizer, that may have been used. Ideally, an explosives analysis will provide enough information so that the origin of the device can be determined.
What are the limitations of the analysis?
Even if bomb squad technicians and forensic scientists can gather extensive evidence, there aren’t always signatures left behind that can lead to the person responsible. For large scale vehicle bombs, such as the one used in Oklahoma City, the size of the bomb made it difficult to identify the fusing system. Another limitation is inclement weather. Rain can wash away explosive residues and make analysis difficult.
How is quality control and quality assurance performed?
During an explosives examination, the analyst’s work is reviewed by a laboratory technical manager who ensures that proper protocols are followed; the technical manager reviews reports and conclusions.
To help standardize explosives analysis methods, the Technical Working Group for Fire and Explosions (TWGFEX) publishes recommended guidelines for Forensic Identification of Post-Blast Explosive Residues for use by forensic practitioners.
The management of forensic laboratories puts in place policies and procedures that govern facilities and equipment, methods and procedures, and analyst qualifications and training. Depending on the state in which it operates, a crime laboratory may be required to achieve accreditation to verify that it meets quality standards. There are two internationally recognized accrediting programs focused on forensic laboratories: The American Society of Crime Laboratory Directors Laboratory Accreditation Board (ASCLD-LAB) and ANSI-ASQ National Accreditation Board / FQS.
What information does the report contain?
If the explosive is identified, this information will be included in the report. The report may also contain details regarding how the device was constructed and how the device functioned. If items of investigative value are developed, this information will be included in the report.
A post-blast report would include pictures, a site diagram with measurements, location, circuitry, explosive (weight and type), components and pieces collected, fingerprints, DNA samples, residue analysis, unique features, links to other IEDs, etc.
The chemical analysis report would provide information on the types of explosive residue and precursors located at the site.
Are there any misconceptions or anything else about explosives that would be important to the non-scientist?
In TV and popular films, a bomb squad technician may be depicted attempting to disable an explosive device by hand in a race against the clock. In real life, however, this is a very rare occurrence. When possible, disabling a bomb is conducted remotely for safety reasons. The only time a hands-on disabling would take place is when a device is attached to someone or in a situation when the area cannot be evacuated in a timely manner.
It’s important to emphasize that people should never attempt to move a device that could be an explosive. Moving an explosive could detonate it causing severe damage to people and property.