I just read an interview online with Bruno Heller about season 5 and here is his exact quote, "The trick is going to be — and this is coming — bringing the audience along and making them second guess themselves and ask, “Is that him? Is that him?” So this is why he has brought Haffner and kirkland onto the show to make us second guess ourselves. With that said, I do not think RJ is kirkland or Haffner. I'm still very curious to know how PJ knew how to go to Brett for help to get Lorelei out of prison. There still is a lot of questions that need to be answered before we can really point the finger at anyone. I have a pretty good theory, but don't feel like posting it tonight. 

Here is the link to the interview http://insidetv.ew.com/2012/05/18/mentalist-finale/