Let me preface this by pasting a summary from IMDB´s description of episode 21:"After Jane finally came to terms with his past, his nemesis strikes once again, commiting murders at diffrent locations seemingly at the exact same time. "This episode is the one after Jane is put on trial for the Red John case, so presumably he manages to convince the jury why he killed Red John, and, more importantly, how he knew that he was in fact Red John.Now keep in mind that there is only one more episode after this, so there is little chance for any more plot twists......therefore I think that the real Red John will finally reveal himself in the final episode.