Two of those murder victims are cops with ties to Nick. One is an Internal Affairs investigator named Martin Nilsen (Daniel von Bargen), who has recommended that Nick be fired. The other is Nick's partner Gus (George Dzunda), who is stabbed with an ice pick identical to the one used to kill Johnny Boz.
Nick discovers Gus' dead body in an elevator, and when Beth arrives on the scene and reaches into her pocket, he shoots her dead, mistakenly believing she is pulling out a gun.
Investigators find evidence in Beth's apartment linking her to Johnny's murder and several other crimes, as well as pointing to an obsession with Catherine stemming from a college romance between the two women. Nick then goes to Catherine's home, where the couple makes plans for a life of peaceful domesticity together before having sex.
Ominous music plays as the camera then pulls back to reveal an ice pick under Catherine's bed, revealing her to be the killer and the mastermind behind Beth's clever framing. While the implication is clearly meant to be that Catherine was behind Johnny and Gus' murders, the ice pick used in their killings had a wooden handle and the one shown under her bed is made entirely of metal, leaving some room for doubt to linger in the minds of filmgoers as the credits roll.
