http://www.sciencemag.org/news/2019/11/scientists-can-now-identify-someone-single-strand-hair

Scientists have developed a new method for extracting proteins from a single, 1-centimeter-long piece of hair.

A new forensic technique could have criminals—and some prosecutors—tearing their hair out: Researchers have developed a method that they say can identify a person from as little as 1 centimeter of a single strand of hair—and that is eight times more sensitive than similar protein analysis techniques. If the new method ever makes it into the courtroom, it could greatly expand the ability to identify the people at the scene of a crime.