Guys check this guy's theory: Theory #8575
This guy casts light on some interesting points from the season 2 episode 8: His right red hand. Red John is one of the policemen escorting Rebecca to the CBI HQ.

Take a look at these pictures (Thanks for the guy who posted them):
http://a.disquscdn.com/uploads/mediaembed/images/682/5550/original.jpg
http://a.disquscdn.com/uploads/mediaembed/images/682/5549/original.jpg
http://a.disquscdn.com/uploads/mediaembed/images/682/4544/original.jpg
http://a.disquscdn.com/uploads/mediaembed/images/682/4210/original.jpg

You all remember the guy who poisoned Rebecca right?
Here's a clear shot of his back:
http://images.wikia.com/thementalist/images/a/ac/Red_John_Disguised_02.jpg
http://images.wikia.com/thementalist/images/a/a9/2x08.png

This mysterious man wears the same uniform as the policemen escorting Rebecca with the blue collar and sheriff-like costume. Why am I saying this guy must be Red John? It's because when he was walking towards Rebecca, she started smiling like when she was talking about Red John and how he brought joy to her life.

Now think for a second, of all the 5 remaining suspects who could possibly disguise himself like that and hustle around the CBI corridors without anyone paying attention to him? Can't be Gale Bertram, Haffner, or Stiles. Bertram is a politician figure, his face is all around the media. Same for Stiles.."Speeches, I give a lot of speeches". Haffner is known inside the CBI, he was a special agent there before he left to create his own firm.

So two suspects are left: McAllister and Smith.
It can't be Smith because I'm quite sure many of us agree with that.

McAllister, not only his uniform resembles that of the policemen escorting Rebecca but he can easily infiltrate CBI'S HQ and do whatever the heck he wants.

I think my message is clear, if you need any further explanations I'll be glad to respond in the comments section.