Airborne human DNA could be used in forensic analysis of crime sites that have been wiped clean of fingerprints and trace evidence, a new research has found.
Offenders are unlikely to totally prevent their DNA from being released into the environment, as human DNA can be found in the air after people have spoken or even so much as breathed, researchers explained.
While collecting trace DNA, comprising human cells, is common in criminal investigations, researchers said "environmental DNA" (eDNA) from solid surfaces, soil, water and air are providing new avenues for gathering evidence.
Comparing samples taken from air-conditioning units in offices and homes, the research team, led by Flinders University in Australia, found that human DNA could be collected on the surfaces of these units and from the air, with air samples likely representing more recent occupation and surface samples representing prior 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.
Biological material is routinely collected from crime scenes and exhibits, and these new methods have potential in identifying the usual users of a room as well as visitors, said Mariya Goray, senior lecturer in forensic science, Flinders University.
"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.
The researchers recommended follow-up studies that can determine the best location for air collection devices, along with the appropriate time after a crime to test and acquire DNA of interest, if it is present.
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