Pipe bombs are the most commonly used Improvised Explosive Devices (IEDs) on American soil. Eric Harris and Dylan Klebold used them during the Columbine High School Massacre. More recently, in October 2018, multiple pipe bombs were mailed to various political figures in the United States.
Depending on who is assembling them, these explosive devices can be a treasure trove of forensic information. Even the most careful bomber is likely to leave behind genetic material that could be used to identify them, including DNA through sweat, saliva, hair or skin cells. There could also be fingerprints.
Traditionally, disabling a pipe bomb to render it safe but intact was viewed as the best possible outcome, giving forensic specialists the opportunity to look for fingerprints and DNA without the corrosive effects of heat and explosion. However, as DNA technology continues to advance, recent studies show detonation vs. deactivation may not matter in the end. What matters most is forensic technicians getting their hands on the bomb, or its components, ASAP.
Forensic Jaws of Life
A few years ago, the Department of Homeland Security’s Science and Technology Directorate developed a tool called the “Power Hawk,” which was originally meant to be a miniature version of the “Jaws of Life” rescue tool firefighters have been using to free trapped victims from car crashes and other dangerous situations for the last 50 years. However, several years ago, the DHS discovered that both the Michigan State Police (MSP) and the New Jersey State Police were using Power Hawk tools on pipe bombs with great success.
The Power Hawk has two major component parts that lend itself well to the extraction of pipe bombs: an extremely powerful hydraulic engine and a pair of scissor-like jaws. The jaws are studded with metal teeth that clamp down and hold the pipe bomb steady. Once the jaws engage, they slowly and smoothly crush the pipe. This causes small fractures that release pressure inside the pipe and prevent the buildup of gases that would power an explosion if the bomb was set off as intended.
Recently, the Rhode Island State Fire Marshal’s Office was called in by local law enforcement to examine a possible pipe bomb. Once they determined the bomb was indeed live, the responders used the Power Hawk to carefully disable the bomb—while not destroying it. With the components left intact, the authorities were able to recover forensic evidence that helped lead law enforcement to the arrest of the bomber.
Analysis after detonation
While disarming a pipe bomb remains the best option, all hope is not lost if the bomb does indeed explode, according to a study from Belgium researchers published earlier this year in Scientific Reports.
In the study, the researchers examined fingerprint and DNA evidence from five pipe bombs in two specific scenarios: using a waterjet disruptor to disarm the bombs without explosion versus complete detonation of the bombs.
After deployment of the waterjet disruptor, the researchers recovered 27% of fingerprints, or 31 of 115. Of the five individuals who left latent fingerprints, prints for three of the five were identifiable post-water damage. Very small amounts of DNA were found on the bomb’s detonators, batteries, metal cans and tape, while significantly larger amounts of DNA were found post-neutralization on the outer holder of the bomb. The researchers were able to generate STR profiles from 9 of 44 collected DNA samples.
After detonation, 52 of 115 fingerprints were detected, corresponding to a total recovery of 45%. The research team was able to develop and/or detect fingerprints from all five individuals after detonation. In all cases, low template DNA was recovered, with large amounts of DNA collected from the components to facilitate DNA profiling. Incredibly, 70% of STR profiling attempts resulted in a positive outcome.
A 2004 study demonstrated a success rate of 20% on components of pipe bombs after detonation. In contrast, the current study shows a 60% success rate after neutralization and 80% after detonation. The researchers attribute this up to advanced DNA techniques that have emerged in the last few years, especially methods that enable analysis of highly degraded DNA.
“This research shows that latent fingerprints and touch DNA on improvised explosives can be successfully detected after destructive conditions and possibly be linked to the perpetrators of such crimes,” the authors conclude.
Photo: The Power Hawk