Mattsson was an inmate at Butcher Bay Correctional Facility and was a part of Rust's gang. He told Riddick that he gives him a shiv for free, only that he has to retrieve it from his bunk. After Riddick had survived the ambush, and came back to Mattsson, Mattsson excused himself by saying he knew Riddick could handle them. Mattson then told Riddick to meet in Riddick's cell. After he betrayed Rust by giving Riddick a shiv behind his back, Rust broke one of his fingers.