@yumararules20 his name is kevin corrigan. He's was in the show Grounded for Life & has been in a handful of Fringe episodes.
The episode itself was great (decent enough murder mystery) but the ending really made the episode worth watching. I really am hoping that Kevin Corrigan is indeed red john and not just another red herring but knowing the mentalist it might just be another red herring. If he is indeed red john than I think they did a great job casting wise. I mean he just said "thank you" to the FBI agent but he seemed like he might have had a red john type of voice.
But if it is indeed a red herring than red john could still probably be someone we've seen before like Bertram or LaRouche or Bret Stiles. I'm still sticking with Bertram he seems to have friends in high places which know red john does. I'm interested to see where they'll take this story.