I have some arguments for accusing Brett Partridge.
1. In Series 2 eppisode 23 there is the scene where Jane meets Red John with a mask. His voice sounds very much like Brett's
2. I beleive that in series like this, the director always tries to inject some subtile details in the filming. No frame or scene is accidental. In Season 5 finale, at the beginning of the eppisode, where Jane arrives at the crime scene, there is a close-up on Brett with Red John's smiley in the back. This illustrates that Brett could be Red John. The scene is aprox at 2:55.
3. In the same eppisode he speaks about Lorelei Martins and gives details.
4. Brett is a forensic investigator, a job very conveniable for a serial killer. He must be in the action.
5. He is thin, thick voice, strange attitude. Usually is boring for a serial killer to be strong and bald, like Gale Bertram.
My opinion is that in a clever series like "The Mentalist" the killer is either every time in your sight(Patrick Jane, Teresa Lisbon), but you don't suspect at all, or he/she appears in few eppisodes and this appearance must give subtile clues about him.
