AC Units and DNA
by Douglas Ankney
Australian researchers at Flinders University have employed a promising new technique to collect and record forensic DNA evidence from crime scenes. A new study appearing in Electrophoresis focused on the DNA retrieved from air conditioning (“AC”) units that circulate a room’s air, including different types of filters at alternate periods.
While a crime scene may be wiped clean of fingerprints, Mariya Goray, senior lecturer in forensic science at Flinders and author of the study, said “it is very unlikely that an average offender, even with forensic awareness, could totally prevent their DNA from being released into the environment.
Samples of Environmental DNA (“eDNA”) from AC units in four offices and four houses were collected at different times following cleaning. Samples were also collected from the air. The eDNA collected on the surfaces of AC units tended to be from previous room occupants while eDNA detected in the air represented more recent occupants. Goray said “[w]e now know that eDNA 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 this evidence to prove if someone has been in the room, even if they wore gloves or wiped surfaces clean.”
Collection of trace DNA is growing ever more important in criminal investigations. In Australia, for example, 62% of all samples processed by Forensic Science SA were trace or touch DNA. But success rates with this type of evidence remains poor.
Source: forensicmag.com
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