HEY GUYS, I'M FROM THE MENTALIST PRODUCTION TEAM. THE KILLER IN FACT IS BRETT PATRIDGE, BUT THE TWIST IS THAT HE IS JANE'S OLDER BROTHER. HE HYPNOTISED JANE IN THE PAST TO FORGET ABOUT HIM IN PAST AFTER HE KILLED HIS FATHER. 
JUST A LITTLE SPOILER FOR THE FUTURE........

partridge, partridge, partridge!!!!!!!!!!!!!!!!!!!!!

For all u haters who are belittling all of us who still believe its Partridge I urge u to read #6373 and if u think u can put that much evidence together for your suspect then by all means. Until u can though read that shut your mouths and let see how it unfolds

Lots of twin and sibling issues on this show since season 1. RJ obviously has a fetish for this sort of thing. So why not one more twin to add to the mix... Could Partridge have a twin? I mean hey, you didn't see the Kirkland thing coming, and you can't say they didn't give us a clue... 

Good job on the mouth thing with Kirkland before he dies. I agree that however it may be that Kirkland left what will be Janes Final clue, For as crazy as this has gotten i gotta say to think of all those suspects in a room together and Jane deducing the final reveal like he does with all the families he solves the murder for is very exciting

I just gotta say that the clues point to him everything, does the Blake poems the fact hes been there since season one. The way he died, I mean come on why leave it as a question, why not have him dead like the way we know kirkland is, of course kirkland isnt because now his brother is a suspect. Im just saying unless it turns out to be a bombshell like Rigsby, which is a sleeper because he is leaving the show and we know Rj is gonna be found soon, but anyway I would feel cheated investing all this time to have it be someone they pulled out of there hat recently Im sticking to what i said years ago Its Partridge and Styles is his Dad I dont care What Plotnick says on his facebook or twitter u think Bruno would let him leak that he would be back.

Brett Partridge was "eliminated" from the show as the first of seven RJ suspects to throw the audience off due to the fact that he was the most compelling and probable RJ.  The most compelling evidence is RJ's unusual voice - it's unmistakebly Brett Partridge's voice.  There are many other clues that you can read in other posts that would lead you to believe without a doubt that Brett Partridge is RJ (his last name (an allusion to William Blake's poem), his involvement in the pilot episode and other critical episodes, etc.).  Brett Partridge and Agent Lisbon have had several moments together (in previous episodes and in his final episode) which proves they were in collusion together.  In the bone investigation scene, Lisbon can be clearly seen to be giving eye signals to Partridge that Patrick Jane is on to him.   

The best clue is Brett's last words ("Tyger, tyger...").  The poem goes on to state, "What immortal hand or eye Could frame thy fearful symmetry?"  Symmetry, as in there are two (twins).  There are two "tygers".  My guess is that Brett has a twin brother.