Joshua Koehler is a trial judge and the father of Marshall Koehler, who was kidnapped by Gregory Brunsen.
He presided over Tyler Brunsen's trial, and after learning that Brunsen was his son, Marshall, and deducing the identity of Marshall's kidnapper, he kidnapped him and took him to his home, where he assaulted and tortured him to near-death. He was later arrested for the act and imprisoned. (SVU: "Liberties")