People, the writer of the show has stated that :
ONE OF THE SEVEN IS RED JOHN.
End of that discussion.
Here is my opinion on it.
1) Kirkland
It won't be Kirkland. That is beyond too obvious and the show doesn't like obvious. I believe Red John attacked somebody he loved too and he is geared to kill Red John himself.
2) Bret Stiles
Not him. Besides being too old to pull it off, Lorelei said "It's a wonder why you DIDN'T become friends as soon as you shook hands". Bret and Jane are friends, which throws this theory out of the water.
3) Brett Patridge
Too young. Realistically, how could somebody this young pull of this level of work? Also too obvious.
4) Gale Bertram
This really could have been him. If you recall from a few seasons ago during the finale, when Jane tricked the mole by telling each suspect a different room, the killer went through Bertram's room first [so they thought it was him] but the killer had rope to go down to the floor below. This could have been played as Redjohn thought that Bertram and the other guy were told different numbers because someone flubbed up, so they figured to check both. However, somebody of Red John's intellect likely wouldn't fall for it.
5) Thomas McAllister [Sheriff]
Definitely not him, too random of a character and not nearly big enough in the series.
6) Reede Smith
Definitely not him, too random of a character and not nearly big enough in the series. He's also too new of a character.
7) Leaving Ray Haffner. He's in it enough, but not enough at the same time to fit Red John. He fits all profiles given. Jane and him don't get along and he's trying to drag Lisbon away and get information off of her. The most suitable suspect.
