Sammy's back story

For those of you unaware, the reason Sammy is the way he is is explained in a deleted scene (that I felt very much should have been kept in)

Nate is reading his file on a break when Mason walks out. Nate asks if the story is true. One night Sammy sets the bed. His punishment for this is that his sister is locked in a four foot tool shed and Sammy is forced to stand guard to make sure she doesn't escape. She is dead by morning. Mason explains "his parents for life in prison, and Sammy got us."