http://www.youtube.com/watch?v=590v4FCm6WU   <----Ok, so, somebody made this theory that the guy in the red sweater could be Red John, and this video explains why...I think it sounds like a good theory, but if you don't believe that one, there is another "guy in red" in that episode who appears pretty sneakily and only for a split second!
If you go to the 2:17 mark in this video, you will see a man in red, running across the background when the cops are about to arrest Jane, one of them being the bald cop who "cleans up" the crime scene.  http://www.youtube.com/watch?v=590v4FCm6WU  I'm not sure if anyone else noticed this guy, and maybe he's just a random background running away from the gun shots, but he could have been telling the bald cop what to do before he went to arrest Jane, then quickly fled the scene.
This is definitely a long shot, but just something to get people thinking I guess.