10 to Midnight (1983)

10 to Midnight (1983) is a thriller based on the real life Richard Speck murders. In this film, we follow a troubled man named Warren Stacey (Gene Davis), who kills women when they reject his sexual advances as a form of retribution. He makes sure they are nearly naked, then stabs them while wearing a pair of latex gloves, being sure to minimize all the evidence perfectly. Detective Leo Kessler knows it's him, but has nothing to prove it, so he decides to plant evidence himself. When Warren gets out of jail on a technicality, he stalks the Kessler family, including the detective's only daughter, Laurie. 

The only redeeming quality this serial killer has is that he commits all his murders totally naked as to make sure no evidence gets on his clothing. That said, Warren commits every. single. one. of his murder nude, showing off his bare butt and balls many times. He may be the worst person alive, but he looks pretty damn good.