Bob Kirkland had the resources. He has the power. He had Jane's files and he had access to the case. Eventhough it is too obvious, I can't disagree with this theory of Bob being Red John.
 By the way, I think I have a theory about why Brett Patridge was killed first in season 6. Maybe because the writers could make a sinister motive behind his death and he was the most accused person on this Website!!!!!