One of the most valuable forms of forensic evidence in cases of male-perpetrated sexual assault is the presence of semen, either in the form of stains left behind on items or on swabs collected from victims after an offense. To confirm that semen is present, suspected stains are examined under a microscope to see if any sperm cells are visible.
Click here for original story, New method to detect and visualize sperm cells recovered from forensic evidence
Source: Phys.org