A Black Veil for Lisa (1968)

Franz Bulon is a police inspector intent on bringing down a major drug ring operating in Hamburg. Thwarted at every turn by an assassin who is systematically killing informants, jealous of his beautiful, younger wife, Lisa, and suspecting her of having an affair (is it real or imagined?), Bulon can scarcely focus on his work. With jealousy nearing the boiling point, Bulon hires Max, the assassin he has arrested for the recent informant murders, to kill his wife...