This isn't a theory on who Red John is but to why Jane was smiling at the end of last episode. (Season 5 Episode 19) well I think that Jane was smiling because he knew that Kirkland had people come in his room and he knew he tricked them by switching information that he has collected with bogus info. He knew he tricked Kirkland. I don't necessarily know if Kirkland is a good guy or a bad guy but I think hes a bad good guy if that makes any sense. Thanks for Reading please post you thoughts in the comments. :)