Shep Native American man who works as a mechanic at Wade's dealership—but he's also an ex-con with criminal connections. He's the guy who helps put Jerry in contact with Carl and Gaear in the first place, facilitating the kidnapping deal.
After Marge tracks him down and asks him to cooperate, politely suggesting that he might get sent back to prison in Stillwater if he refuses, Shep finds Carl and beats him viciously with a belt for leading the cops to him. Shep really loses it in this scene; he almost kills Carl. It's a shockingly violent scene. His previously emotionless demeanor totally breaks down.