The Killer Inside Me http://www.imdb.com/title/tt0954947/
Set in the 50's, a small Texas town's deputy sheriff is helping the richest man in town pay hush money to a prostitute that's been sexing up the richest man's son -- to buy her silence before and after the son gets married, so there's no scandal.
Except the deputy goes a little psycho.
Another movie starring an Affleck - although this time it's Casey. Plus Kate Hudson and Jessica Alba and Ned Beatty.
The movie has some very violent scenes, so if you have trouble watching them be prepared to cover your eyes.
(My way of gauging if scenes are too violent is if the wife covers her eyes during the scene. If she covers her eyes AND asks me to mute the sound - watch out!)
Pretty darn twisted in ways too. You have to be patient to see how the seemingly disjointed things near the beginning of the film fit together into a coherent story. Once they fit together the rest of the film is a breeze to keep up.
So if'n y'all like thriller/crime/drama with violence and psychotic behavior this is worth the watch.
And no, Ned Beatty does not crawl around on all fours in his tighty-whiteys squealin like a piggy. I think to date there's only one film he does that in, so let him live it down, eh?