Ending *SPOILER*

In the very end it turned out to be her own husband who was the guy who shot at the other guy in the car... he purposely took and wore the cowboy hat and stood facing away to look like the other guy he was with...

When Jamie Luner tracks down and discovers it's her husband, and the fact he's still alive, they're in a cabin in the mountains, basically the husband had entirely taken over the guy he murdered's identity and life... that was the guy's cabin Jamie Luner found her supposed to be dead husband at.

So to make it crystal clear, at the beginning of the movie, the husband killed his buddy in the car, took his cowboy hat, and switched identities to look like he was the other guy from the back when his wife was looking outside the window witnessing the murder... she was thinking the cowboy was murdering her husband, when in fact it was the husband murdered the cowboy... he set the car on fire on purpose to char and burn the cowboy's body so the police were unable to identify it.

When the wife (Jamie Luner) is one the run for the murder after her husband set her up for the murder of him, she over the course of the movie collects pieces of evidence in order to clear herself of the crime as well as locate her husband's murderer (which whom she thought was dead of course)... He tries to kill her by attempting to drown her in the river/creek by the cabin of the guy he killed/guy he hijacked his identity.

But in the act of trying to drown his wife... the bounty hunter who was helping her, after multiple verbal warnings, shot her husband, more than likely in a way not to kill him, but to injure and disable him from letting go of his drowning wife and she was able to get away. The police arrive, and the husband is strapped to a gurney, he is conscious as they wheel him away. Jamie Luner's stepdaughter comes running up and they embrace.