Facing the Enemy (2001)

He made one mistake... He slept with the killer's wife

Griff McCleary is a cop, now his son shot himself with Griff's gun. A year later both he and his wife are still reeling from it. Griff feeling shut out by his wife Olivia, decides to move out. Now he is investigating what appears to be a murder-suicide. He believes that there was no suicide. His investigation leads him to a girl named Nikki.