Nicholas "Nicky" Roberts is the stepson of Hank Roberts, who abused him and his mother Sandra and forced Nicky to join a fight club. During a fight, he accidentally beat Ethan Gilbert to death. When Hank was later found murdered, both Sandra and Nicky became suspects.
However, as both of their fingerprints were found on the gun used to kill Hank and both admitted to killing Hank while denying the other one killed him, the case against them was dismissed. (SVU: "Pop")