The sneakiest burglars slip by unnoticed, but they leave millions of their own witnesses at every crime scene. Researchers have found that it may be possible to identify criminals based on the microbes they shed from their skin or nostrils.

In 2014, Jarrad Hampton-Marcell at Argonne National Laboratory in Illinois and his colleagues showed that people seem to leave a unique microbial signature in their homes . This suggested that the microbes people leave behind could be useful for identifying suspected criminals like burglars. “What if we could potentially find …