The Strangler (L'Etrangleur)

Released at the height of the Boston Strangler killings, this film revolves around lonely and disturbed hospital lab worker Leo Kroll (Victor Buono). Though he's a meek technician while at work, he leads a double life as a deranged killer of young women -- particularly nurses. But a chance meeting with Tally (Davey Davison), a young lady who works at an amusement park, influences him for the better, curbing his homicidal impulses and restoring for him some semblance of a normal life.