Steven Wench is an FBI agent, infiltrate in Visualize to discover Bret Stiles' crimes. In fact, Stiles (and Patrick Jane) discover his status of "mole"; Stiles sent him false clues.
As "Brother Steven", he was one of the teachers in the cult. In this group, maybe, was present Red John's accomplice, Ron Deutsch.
Some fans has suspect Wench to be Red John (see Red John Theories).