Australian researchers manage to recover DNA from air conditioning

It feels like an episode of the series The experts : we can now know if a suspect was in a room, by recovering his DNA in the air conditioning. This is what researchers from Flinders University in Australia have just demonstrated. In fact, DNA is released in microdroplets of saliva when we breathe or in microscopic fragments of dead skin when we move. It remains suspended in the air for a long time and ends up being collected by the air conditioning filters. By analyzing them, we can know which people have passed through the room, even if we have taken care to clean all traces with alcohol. It is very difficult to prevent your DNA from getting into the air.

DNA trapped in the filter for several months

Researchers have shown that we can also collect this DNA with the same type of device that is used today to detect Covid in the air. The only problem is that it is only effective over a shorter period of time. Because the DNA can end up falling to the ground, clinging to objects or, quite simply, being evacuated if you open the window to ventilate the room. On the other hand, if there is air conditioning, as we only recycle the indoor air, the DNA can be collected several weeks or even several months later, since it remains trapped in the filter. This could therefore provide an additional weapon in the “cold cases”, the famous unresolved cases.

For now, these are just experiments. Before using it in investigations, it is still necessary to define precisely how long after a crime DNA can be recovered in air conditioning. And when there is none, what is the best technique to collect it directly from the air. This proves, once again, the importance of forensic science in resolving investigations.