I do believe it is Walter Mashburn, .  In the episode Red Line he is someone who "reads" Lisbon right off as Jane would do.  He is amused by Jane and challenges him and Lisbon by saying "catch me if you can" even though he knows he's was not the killer in this particular case.  He seems to want to be Patrick's " buddy" much like Red John who wants Jane on his side.  When Jane finally does catch the killer in he is impressed and finds it exciting.  He also tells Jane "maybe next time I'll be the killer" 
Also, as we know Red John is a character that seems to be able to get anyone to do anything.  This Mashburn character literally "charms the pants off" of Lisbon in a later episode which is not easy to do.  

What if PJ and lorelei made the video together to test Lisbon and the others at the CBI. That way PJ would know if one of them was a RJ accomplice

Question that just popped in to my head:
Why didn't Jane just rush to Bertram's office as he was on the phone with Red John? And if he would be in his office then Jane would have one less suspect on his list, right?

Question that just popped in to my head:
Why didn't Jane just rush to Bertram's office as he was on the phone with Red John?
And if would be in his office then Jane would have one less suspect on his list, right?
Perhaps the clue Heller was talking about?

Ok- in my previous theory 4702 as crokus, my guess was Partridge. I stand by my previous guess.

Now, this whole CBI Ron theory is becoming interesting. He IS literally in every episode minus the ones that directly deal with RJ, except Ron is one of many characters suspected to be Red John (see Red John Theories). Since working at the CBI, he appears in almost every episode and in many RJ episodes, except Red John's Footsteps, The Blood On His Hands, Red Moon, Strawberries and Cream, Scarlet Ribbons, The Crimson Hat and Blinking Red Light.

He is the only REAL " where's Waldo" character, that Bruno heller speaks of. There is also a youtube video where Owain Yeoman (Rigsby) and dovovan (cbi Ron) talk about Ron being RJ

http://www.youtube.com/watch?v=0llrwyH08Sg&NR=1&feature=endscreen

His posture, crossing of the legs does match.. They could just be messing with us..

Next, I no longer put any faith into what Bruno Heller says! Here's why...
In the Strawberries and Cream pt 2 episode.. If you put the subtitles on during the part where Teresa calls red john after she shoots Craig OLaughlin- when timothy Carter answer the phone, the subtitle depict his name as "ROSS" - not Red John , not Timothy Carter- but ROSS-

Why? Because Bruno Heller intended him to be the REAL RED JOHN.. We disnt even learn the name timothy carter til the following season premier. Right? I think that it was supposed to be the end of the RJ saga- but in between seasons, Bruno Heller realized that his ratings would drop if there was no more Red John. So they continued on with the story.

And you never hear of or see the name ROSS again..