In a significant finding, researchers have for the first time identified human DNA in household dust -- a breakthrough which they claim could be used in future to trap murderers and thieves by proving their presence at a crime scene at a certain time. So criminals beware.

Although the amount of DNA recovered is tiny, according to the researchers, further study could find ways of recreating someone's profile or even working out how recently they'd visited a crime scene from the decay of their DNA. "The discovery that human DNA is detectable and measurable in dust is a first. People have quantified the amount of DNA in dust many times before, but no one had looked before for human DNA," co-researcher Bonnie Brown said. Brown and his colleagues at Virginia Commonwealth University in Richmond collected dust samples from various rooms around their campus, from highly trafficked classrooms to quieter offices. Most of the DNA they recovered came from bacteria or fungi, but there was human DNA in all except one of their 36 samples, the 'New Scientist' reported.

Though each sample contained just trillionths of a gram of DNA, it was more than enough for amplification and profiling via the DNA kits used in forensic labs, according to the Virginia team. But the read-outs contained overlapping signals from so many people that it was virtually impossible to pick out any one person's DNA profile. However, technology may overcome this obstacle, the researchers hoped.

The results of the study have been published in the latest edition of the 'Forensic Science International' journal.