This was just released by CBS.
ON BEHALF OF ABC STUDIOS AND CBS PARAMOUNT NETWORK TELEVISION:
"Last week, Mandy Patinkin asked to be released from his role on Criminal Minds. We have honored this request, which was not in any way connected to contract renegotiations or salary issues. His departure from the series will be explained to audiences in an episode to be filmed in the near future and broadcast early next season. We thank Mandy for helping to make Criminal Minds a strong and successful series, and we wish him the best in his future endeavors. A new character will be added to the series for next season."
ON BEHALF OF MANDY PATINKIN:
"Due to creative differences, Mandy has asked not to return to Criminal Minds this season. Mandy would like to thank the studios and network for releasing him from the series and he wishes the cast and crew continued success in all of their endeavors and looks forward to continuing to work with the Disney and CBS companies in other capacities in the future."