Guys the clue that Heller was talking about from the second episide is infact two clues. One was the hand red john used two hold the knife and the second obvious clue was the pigeons.
On episode 3 the sheriff used his left hand to help jane from falling and jane noticed that if you look closely and then there is the music in the background. And look how the sheriff reacted to the pigeon ......we also learn that he is much smarter than he puts out to be, look at the way he analysed the dead guy. Sheriff Thomas McAllister has been there since the beginning and yes he is definitely RedJohn as you will find out. His accomplices were Bret pattridge, Reede Smith, Gake Betram and Ray Haffner( who happens to ask Lisbon if he was tracking the seven suspects? ......

With the next episode revolving around Haffner, I thought this was the right time to put in a theory. 
-From the physical description from Rosalind, Haffner fits the best.
-He is the right age (5x13) 
-In the episode Haffner first appears in Lisbon tells Jane that "He was an FBI agent in the Organized Crime Division, and was an expert in wiretaps and creative surveillance techniques". In the season 1 finale we see that Red John has set up some surveillance to watch Jane and I don't think any of the other suspects have expertise in surveillance. I'm pretty sure RJ has set up other types in other episodes but I would need to look back.
-He works for Visualize and he used to work for the FBI both have some type of connection to RJ.
-Lisbon already thinks that he is Red John.
-This might not mean much but Haffner's first episode was wrote by Bruno Heller and it shown Jane shaking his hand.
-I thought it was strange how he asked Cho if he was smarter than Jane.
-He's an excellent whistler.
-If Haffner was Red John it would explain why he left Lisbon alive.

If Haffner isn't Red John I would say that it's Bertram, but with 5 suspects left it was always going to be tough to decide. I would say there is zero chance that its Reede Smith though.