Right now, I chose SOMEONE ELSE, but only because we have multiple suspects, I think this week's episode, clearly made a statement of the suspects, the first page includes Partridge, Ellis Mars, Dean Harken, Jason Cooper and Walter Mashburn, it can't go beyond this 5. On the other page it has other names but for different reasons they don't seem to fit the profile of Red John (who is still alive, for example).

On the other hand, I am surprised that the guy from Homeland It's not on the list...he is the last one that we saw Patrick shake hand.