Penn State police filed charges in 12 cases, all involving a man who entered residence halls and other campus buildings, found women alone in their dorm rooms, lounges, laundry areas, restrooms, even laboratories, and masturbated in front of them.

In some cases, police said, the victims reported that the man, who usually wore a surgical mask or ski mask, tried to touch them or touch their breasts.

At first, he fled when they screamed; as time went on, police said he'd ignore their cries and continue to masturbate. Sometimes he maneuvered to trap or hold them in a room until he was done, according to police accounts.