I only saw the last 15 minutes or so of the movie so hopefully you can tell me what it is. There was this serial killer and this girl who were fighting by water and he was drowning her. Then they both fall in the water and struggle. I remember the guy saying that she didn't have any skills like the other members that he killed and he didn't know why she was there. Apparently she can hold her breath for a long period and they both had guns sticking out of the water waiting for whom ever came up first. The killer came up and she shot him in the neck. She thought he was dead but he wasn't until her friend shot him in the head and then he was dead. There was another scene where the killer rigged a gun so it like backfired or something and a guy went down in the elevator with it. When it opened he fired and killed himself.

Mindhunters (http://www.imdb.com/title/tt0297284/)