It's Haffner.
When Jane releases the Sofia's [Jane's psychologist] record, she describes Red John. 
-Middle age, He strengthens - good condition, good structure
- He has many friends - because he is member of the visualization
- excelent whistler - It was meant to Sheriff, but when Ray left Lisbon in hospital, He was whistling
- When Sofia is describing 'damage of the narcistic personality' camera focus on Stiles, but on the right is Ray Haffner.
- When Lisbon asks him, if he was ever been on the farm, he just avoids the answer

Sorry for my bad English. I tried to write clear. I'm from Czech Republic.

What do you think? :)