I had a different theory before, but now I believe Gale Bertrum i s Red John.


         First, he has close connections with Bob Kirkland, a strong suspect. 
                        Secondly, when they were trying to trap red john before,  Bertrum made a -phone call just before Patrick Jane  unvieled his trapp at the4 hotel.

                                                   And I believe that Gale Bertrum was the first name the Jane revealed in his 7 suspect list of Red John,  explaining the leak in the CBI for all of the information ertaining to Red John.