This is an American film that I saw probably early 90's. There's a killer on the loose. He targets women, and afterwards cuts the tops of their breasts off. Towards the end, they think they found the killer and all is well. The female protagonist, maybe a detective, not sure, is looking for something at her boyfriend's place. She finds a hidden container. She opens it and discovers a set of nipples. It turns out her boyfriend was the killer. Boyfriend catches her, and then chase ensues.
Sorry I dont have more, but this one scene is all I remember.