first of all, theres a tigertiger organisation going on which makes it very hard to define who is red john and who is just a member(might be both, since rj would be perfectly cloaked)

second thing that comes to my mind, WHY did redjohn kill brett partridge?

2 possibilities imo:

. he was part of his cult and was a weak part(HOWEVER why would he know redjohn personally?)
. he isnt really dead...what a way to get removed from the list(very tricky but genious)

what makes me think of option 2 is: we never did see the dead body...lisbon got attacked from behind when she turned her back to pj(s6.1)...and again WHY would they kill him in episode1, since not even jane could see if he tells the truth by starring at him("either he tells the truth or he is a very good actor-which red john should be)

spoileralert!