Explosive discoveries from trace DNA

The warning bellow “Fire in the hole!” from the county fire marshall is heard seconds before a pipe bomb detonates in a shipping container at a fire training facility in Conroe, Texas. Dr. Sheree Hughes and her students, dressed head to toe in bright white and yellow personal protective equipment (PPE), grab brooms and brown evidence bags, readying themselves to start collecting minuscule traces of DNA on the tiniest bomb slivers.

After the pipe bomb explodes with its tell-tale boom – and they get the all clear – the forensics research team enters the shipping container, first picking up larger fragments of the bomb, then using specialized brooms, with bristles covered with protective paper, to gather up the scraps and shreds that remain into the waiting evidence bags. They will then test different DNA collection techniques to see which gives them the most material to work with for identification purposes.

“These are tough types of samples to collect for evidence and identification,” says Hughes, in a textured Aussie accent, lingering a bit on vowels. “When someone touches an improvised explosive device they only leave trace amounts of DNA to begin with. The heat from the explosion then further degrades that DNA.”

That’s why, the day before, the team spent a few hours at the shooting range, picking up spent bullet casings (as well as swabbing the slides, triggers, and grips of guns) that were shot by local law enforcement volunteers – and will later head to Sam Houston State University’s Applied Anatomical Research Center (AARC) facility, one of the nation’s few so-called “body farms,” to take collection swabs from a willed donor cadaver. Hughes’s research is guided by one overarching goal: to obtain as much genetic information as possible from small, degraded samples. She is trying to improve retrieval of trace DNA from bomb fragments and firearms, as we as obtain information from minuscule amounts of tissue from decomposing and skeletal human remains.

Behavior information out of 15 cells

“If we can find out what methods of collection and preservation work best, giving us the most information and different ways of looking at genetic markers, we hope to provide more definitive identification, whether it’s a person of interest in a terrorist attack or the victim of a crime or a missing person case,” Hughes says.

Out of just 15 diploid cells, forensic scientists today can extract information such as whose DNA it is and the ancestry/biographical origin. Expanded and refined panels allow identification with increasingly more geographical discrimination and phenotypic information like eye, hair, skin color, face shape, height or biological age. Even newer is the ability to search for behavioral information, like whether someone is a smoker or exhibits antisocial behavior. In the case of molecular autopsies, scientists can glean medical information to assist in determining the cause of death.

Flexible Workflows

Sheree Hughes credits QIAGEN with helping her team develop new and improved workflows. “QIAGEN pretty much has a solution for everything,” she says, as one of her students loads the QIAcube with samples from the past two days’ events to prep them for further analysis. “One of their strengths is being able to provide a solution in each area of the workflow and since they take such a modular approach to those solutions, it is easy to switch them in and out, so you can figure out what works best with particular applications.”

The flexible workflow that QIAGEN provides, as well as their reliable, robust chemistry, she explains, is what gives her and her team the freedom to investigate different collection and extraction techniques, particularly when it comes to DNA extraction. “We want to capture and collect as much DNA as possible from a sample from the start,” she says. “With QIAGEN’s depth of scientific knowledge and experience, it’s really their cornerstone, we can better recover and extract DNA from our samples.”

She points out QIAGEN’s short tandem repeat (STR) kits, as well as DNA quantification kits and massively parallel sequencing (MPS) panels for missing persons, as tools that support her team in their research. “QIAGEN products are unique to the field,” Hughes says. “They give us what we need to collect more DNA information from less and less of a sample and that gives us even more opportunity to identify persons of interest in crimes, as well as missing persons or casualties.”