I noticed one very interesting thing from the list of 7.I dont know if its really important but its worth to mention it.From the 7 suspects of the list there is only one of them whom his appearance on the show isnt connected at all to the Red John case.And this man is Sherrif Thomas McCallister.In his appearance in s01e02 we have zero mention to Red John and it seems one episode with another killing that PJ and the team will solve in a smart way.Think of it.
1)Brett Partridge:All his appearances except one were in episodes referring to Red John.
2)Bret Stiles:Helps PJ to get Lorelei out of prison and also in another episode talks to PJ about RJ and how RJ takes all the things from PJ's life.
3)Gale Bertram:He is also connected to the Red John case in s03e24 where we thought at the beggining that he was RJ's accomplice before we find out that O'Laughlin is RJ's accomplice.
4)Reede Smith:His only appearance is in s05e01 where he and Mancini at the beggining have an argument with Lisbon and her team about the Red John case.Also take a look at his face when Rigsby says "We were this close on catching Red John...etc".
5)Bob Kirkland:Well what can i say about BK.He killed Jason Lennon.He is the chief in finding Lorellei when she escaped from prison,he break into the room of PJ.All his appearances are connected to the Red John case.
6)Raymond Haffner:S04e01.He and his team replace Lisbon's team cause of their suspection in killing Timothy Carter(fake RJ).And of course s05e13.The episode that we learn that RJ started to kill in the late 80's and was a member os Visualise as Haffner too.