DNA In The Breeze: Forensics Embraces Airborne Evidence

New research has discovered that airborne human DNA could serve as a valuable tool in forensic analysis, particularly in cases where crime scenes have been thoroughly cleaned to remove fingerprints and other trace evidence.

According to researchers, offenders are unlikely to completely prevent their DNA from being dispersed into the environment. This is because human DNA can linger in the air even after individuals have spoken or simply breathed.

While the collection of trace DNA, which includes human cells, is a common practice in criminal investigations, researchers note that “environmental DNA” (eDNA) extracted from solid surfaces, soil, water, and the air offers promising new avenues for evidence gathering.

In a study conducted by Flinders University in Australia, researchers compared samples collected from air-conditioning units in both office buildings and residential homes. They discovered that human DNA could be detected on the surfaces of these units as well as in the air. The researchers noted that air samples typically reflected more recent occupancy, while surface samples indicated previous occupation.

“Our study also showed that air circulating through air-conditioning could collect human DNA, which further supports the idea that human DNA can be found in the air and settle on surfaces,” said Emily Bibbo, a PhD candidate at Flinders University’s College of Science and Engineering, and author of the study published in the journal Electrophoresis.

Mariya Goray, a senior lecturer in forensic science at Flinders University, mentioned that traditional collection of biological material from crime scenes and exhibits could be enhanced by these new methods. These techniques hold promise in distinguishing between regular occupants of a room and visitors.

“It is very unlikely that an average offender, even with forensic awareness, could totally prevent their DNA from being released into the environment,” said Mariya Goray. “We now know that eDNA and eRNA shed from sources such as skin or saliva can be detected in the environment, including soil, ice, air and water.” “We may be able to use (eDNA) as evidence to prove if someone has been in the room, even if they wore gloves or wiped surfaces clean to remove the evidence,” said Bibbo.