After the episode "Red Listed", a group of shadowy police figures were confirmed. They all use the phrase "Tiger Tiger" as a sort of password. I think that Red John is not a single person. But an alias used by multiple people within the organization. For sure Bertram,McAllister, and Smith are part of this group . This group might have ties with Visualize so Stiles and Haffner may also use the Red John alias . Also the last thing Brett Partridge said before he died was "Tiger Tiger", so he might be a part of the group also, and was killed off by one of the other members.
In conclusion, I think Red John is everybody on Jane's suspect list EXCEPT Robert Kirkland.
