When Rebecca was being escorted to her cell her facial expression showed that she saw Red John right before he put the poison on her hand. She was giving him that crazy-eyed adoring smile. Wouldn't the guards who were walking with her have recognized him if he were already a member of the CBI?

Fyi: I just read an interview with Bruno Heller by Entertainment Weekly. He said that RJ is definitely one of the 7 suspects on the list. He is not tricking us. He said there will be no more tricks, and i understood him to say that we will find out the truth next season. He also said, definitively, RJ is NOT Patrick Jane. Thank goodness. That would be heartbreaking and devastating.