Whoever watches the show criminal minds, what happened to gideon?

Gideon began to have doubts about himself and the work he was doing at the end of Season 2 when he dealt with a serial killer named Frank who knew as much about Gideon as Gideon knew about him. Then in the beginning of Season 3, the team was working on a college campus and had a suspect in custody when someone else got killed. By the 2nd episode of Season 3, Gideon had left, leaving only a letter for Reid at his cabin. Gideon has not been heard from since that time, last we saw him, he was at a diner telling the waitress he was going somewhere but he wouldn't know where until he got there. In reality, Mandy Patinkin and the show execs had "creative differences", whatever that means.