I think that Kirkland is Red John because Red John has to be a very powerful figure to do all the things he has done. Also Red John was able to figure out who was on patricks list so since Kirkland had those two agents break into patricks office it makes kirkland a probable suspect. Also Rosalind Harker probably would not have been attracted to an old man like bret stiles. I know that she is blind but I think that she would be able to tell if red john was old. I dont think red john is brett partridge because he is to young and red john has been killing for a long time. Remember in the episode red barn when the team figured out that red john was a member of visualize 25 years ago? Well Kirkland looks like the perfect age for that. Brett Partridge has the voice of red john but he is too young he is second on my list though.