For the last decade, police in Tokyo -and now in Osaka- have been using forensic techniques to nab men who grope women on crowded trains (when women-only train cars are not enough). The technique, usually used to comb crime and accident scenes, allows to to lift tiny traces of fabric fibers from a suspect’s palm and match them with the victim’s clothes.

A sticky film is pressed on the suspect’s palm. The film can pick up micro-fibers about a hundredth of a millimeter in length. The particles are then compared to fiber samples from the victim’s clothes. Both are put through a microspectrophotometer, a super-powerful microscope that measures light waves. If the fibers match, it proves that the suspect’s hand had come into contact with the woman’s clothes. A hand casually brushing against someone’s clothes would not leave fiber residue, police said.

According to the Tokyo Metropolitan Police Department, since 1995 the police have been applying forensic screening to about 150 molestation cases a year.

Via news3yen Asia news.