I think it's either Kirkland or Haffner but right now i'm more on the Kirkland thing. First of all the theories before about Kirkland make much sense too me regarding the name-switching. 

I think Michael was killed by Smith so he could fake the death of his brother, who is red john. This was done to protect Red John and lead Jane and all the others to the wrong path.

When I saw the meeting of Kirkland and Reed Smith it felt really strange how Kirkland was trying to convince Smith of joining his work against Tyger. It looked much more like a trap for me, to support the two brothers in their plan