I'm changing my answer after last night and after reading an interview with one of the writers. WARNING, me quoting the article may contain SPOILERS. Here is the link..newer article compared to other TV Guide article.So with the quotes below and what we heard from the other article...Jane stands over him and kills him in the park. RJ came out in the open for this too. Stiles is a dying man. He has nothing to lose...thus why he would come out in the open at the park. Also, last night when all three men had the tatoo, Stiles is the one who said "Patrick, look." I think he is leading him along. Stiles and Patrick always had a bond that would fit. Also, if Stiles was dying, this may allow PJ to not actually have to kill him but watch him die in the park...so no hands getting dirty. Just makes more sense. The one rub in this is Stiles has been weak and wouldn't have strength to kill. But maybe that is where Visualize and Tyger/Tyger come in.

http://www.tvguide.com/News/Mentalist-Fire-Brimstone-Recap-Jane-Red-John-1073216.aspx

Does that make the case for Stiles being Red John stronger or weaker? On the one hand, is he physically capable of committing all these murders? On the other hand, he might be motivated to finish his mission before he dies.
Woodruff: You brought up both sides of it, which is exactly what we were sort of hoping for. He is a Red John suspect. I think he's been one of the strongest Red John suspects since his character's introduction, and you get to see him I think in a vulnerable way that we haven't really seen him in before. He's on the run. He's trapped by the FBI. He's forced to live sort of like Julian Assange in this consulate. So maybe what we're hoping is you think a little bit less of him. You think maybe he is on his way out and not capable, just because you sort of seem to feel a little empathy for him. On the other hand, if we are getting to the end of Red John, it's sort of perfect timing. Maybe he's resolving some final things. And the line "a dying man does not fear death" I think could mean a lot, just given how truthful that can be. He has nothing to lose at this point.

We've heard Red John's voice before and it doesn't match up with any of the suspects. How will the show resolve this?
Woodruff: We definitely will deal with that, and I think it's done in a really, really great way that's going to be coming up in [Episode 8]. ... We were very aware of that and conscious of it going forward and in dealing with Red John and [his] voice and all that stuff. So it definitely pays off, and faithful viewers will, I think, be satisfied by it.