A Killer Among Us (2012)

In the small Oregon town in which she lives, Helen Carleton is shot dead point blank four times execution style outside her pet store. There are no eyewitnesses. She is survived by her husband, Nick Carleton, and their three children. After three months, Detective Joe Moran, the lead investigator on the case, officially closes it unsolved, which doesn't sit well with the family. However, he is still working on the case unofficially as he believes that Nick arranged her murder. As such, he asks the eldest Carleton offspring, high school senior Alex Carleton, to assist him on the case, which is against the law as she is still a minor, who would not be under the guidance of her guardian. He doesn't initially tell Alex why he needs her help, but Alex is more than willing to provide whatever assistance she can to catch her mother's killer. When Detective Moran eventually tells Alex his belief about Nick, she is initially reluctant to "spy" on her father. But Nick's behavior - getting rid of everything related to Helen from the house, wanting to be buddies with his children more than be a father figure, buying expensive gifts for them some which would have been against their mother's wishes, and not taking on any of the domestic duties of the house leaving those all to Alex - and Alex's stronger want to find her mother's killer lead Alex to continue to assist Detective Moran, which includes not being able to tell anyone, including her siblings, her friends and obviously Nick, what she is doing. This task becomes all consuming for Alex, whose personal life, academic life and emotions take their toll because of it, mostly because she can't discuss what's going on with anyone but Detective Moran, and as she views her father in this different light. Their work may all be for naught if the authorities find out Detective Moran's less than legal and ethical goings-on with Alex. But more importantly, her life could be in danger if the killer, regardless of if it's Nick or not, finds out that she is actively looking for clues, and her relationship with her family could be irreparably damaged, especially if Nick is not the killer.