Georges Tabet

Peter is a laborer who dons fancy clothes and cruises the seedy dives of Dusseldorf for women. Whenever he is rejected by one of the females, he turns into a sadistic murderer. A shy young cabaret singer falls for Peter, but she too becomes a victim of his rage.

Tells the story of a widow who begins to receive blackmail letters demanding money as almost everybody has disliked her husband in a small town. (Wikipedia)

Alain Revent, a seductive and refined man, derives a peculiar satisfaction from debasing his wives. The first, driven to the brink of despair, throws herself out of a window. Enlisting the help of an equally perverse casual acquaintance, Dino, the "handsome brute" proceeds to emotionally torture his second wife, Nathalie. The sadistic plan is picked up on by Officer Leroy who suspects the truth. (imdb)