Touch DNA and Jon Bennet Ramsey
It sounds like something out of science fiction or something from the future, but it it a done deal that sometimes truth is stranger than fiction. This may be a trend as the world moves on and science progresses. Touch DNA proved that her parents and all members of the family were innocent of her murder.
When we think of DNA from a crime scene semen and blood come to mind. We don't think in terms of the invisible man or in this case, the invisible cells. Humans leave a trail of DNA everywhere they go and is why our mattresses are full of dust. As we touch the TV, stove, our clothes, or anything we leave skin behind and genetic material the eye can't see, but it can be detected by touch DNA testing.
It gets a little trickier to find the right DNA material when investigating a crime, but not too much so because the investigators have to guess where the perpetrator might have touched the victims clothing or another object. With educated guesses they begin to scrap the spots where they think the cells ought to be and then they test to see if they found any useful genetic material.
In Bennét Ramsey's case, there were two places on her long johns that were scraped and from, which the evidence was found. Hopefully, such DNA testing will help catch her killer and many others. They should learn to keep their hands and everything else to themselves.