Detective Denillo (Joe Mantegna) encourages the McCanns to find a support group for dealing with a family loss. He also puts her mind at rest that there is enough DNA to catch the killer. Karen begins going to the support groups and finds people going through the same thing she is. Denillo tells her they caught the guy responsible for the death of her daughter and there should be no problem in convicting him based on the DNA evidence.
Robert Doob (Kiefer Sutherland) is charged with the crime and his DNA matches, but because of a technicality his case is thrown out. Determined to find something to make Doob pay for his crime, Karen begins to track his every move to the point of stalking him. He turns the tables on her and begins a conversation with her younger daughter at her school. Knowing there is nothing anyone can do.
Karen is told she needs to stop her fixation on getting Doob and start focusing on what she does have. She has neglected her work, her daughter, and her husband. She starts building those relationships back up when Doob intimidates her again. This begins her plan of setting up Doob and killing him. Having a plan revamps everything in her life.
She devises a plan to get Doob into her house. Doob falls for it and is killed by Karen. Karen makes it look like self defense, but Detective Denillo sees right through it. There is no evidence to charge Karen, so it goes on the record of self defense.