If Jane is going to get away with murder again (still can't believe he did the first time, but I digress) when he finally kills the real Red John, what is the only way he can do that and get away clean (assuming he's not acquitted of murder again in some idiotic trial)?

Kill somebody who is already, officially dead and whose faked death could never be revealed because all the accomplices had the 3 dot tattoo?

Partridge.