Okay... I remember watching this film when I was young.. I remember some scenes.
there is a family living in a forest, wherein a suspicious killer/criminal seems to act as a carpenter/helper to the family. he lives in a mobile home with his girlfriend whose sister is a cop and hates his boyfriend for he looks suspicious.
description: the killer looks middle age I think, and the girlfriend is young. later at the end of the film, his girlfriend visited her sister at the office and found her sister lying in the ground (I think she's alive, even if her throat was slit)
the killer is a pervert, he even tries hitting on the guy's wife living in the forest.
the wife I remember has two kids, a girl and a boy (I think the girl is older, maybe age 12 or something)
in the end, the killer was killed by the husband and saves the day.
thanks for helping :)