Love and Bullets(1979)

Jackie Pruit is the girlfriend of notorious gangster Joe Bomposa. When it looks as if Bomposa's goons are threatening Jackie's life, the FBI moves in to protect her, hoping that she'll have incriminating evidence. Veteran agent Charlie Congers is assigned to watch over Jackie, and while it soon becomes apparent that she knows almost nothing about Bomposa that would be of any use to the FBI, he falls in love with her. Bomposa decides it would be more convenient to have Jackie out of the way, ordering her to be executed. Bomposa's henchmen slip through FBI security and murder her, but now they have to answer the angry and vengeful Congers.