Kenny Bixton is the younger brother of hate crime victim Rudi Bixton, who was brutalized out of hate over his obesity. His attackers insulted him by comparing him to a pig in a sausage factory, beat and stomped him enough he was confined to a wheelchair and his arm got gangrene, and left him unable to work and keep his job.
He teamed with his sister Mia Bixton when they came across Jessica DeLay with Rudi's hat and realized she was one of Rudi's attackers. To avenge Rudi, the two siblings beat her, raped her with a baseball bat, and cut off one of her fingers, which was reattached on her hand in time when she was rushed to the ER.
The younger brother and sister were found and taken into custody. After Detective Lucius Blaine nearly manipulated Mia to confess with a false promise of because she's a kid with her first offense, she'd be exonerated, Donald Cragen ordered a more procedural approach. To save the investigation, Blaine and Elliot Stabler were more sympathetic to Rudi, which was enough personally for Kenny and Mia to confess.
They were both found guilty and imprisoned, but their confessions reduced their sentences because they went along with the justice system. (SVU: "Fat")