i think strngly that Red John is Haffner (who ele could be )
after seeing the last 2 episodes ,Jane assumed that red john is the one who tried to bug the cbi office and that's how he knew that "red john " has a tatoo on his left shoulder .but that was a trap 
well i think that red john is aware that some powerful people (the tyger squad ) are using his name to to commit their crimes and we know red john don't tolerate those actions (we know what he did to Lorelai ) and he is also aware about the tatoo so he made a fake a fake tatoo on his shoulder and killed that girl so he can set up Bertram Maccalister and  Smith.
that's live us with Stiles and Haffner 
well i don't think it's Stiles becauz he once helped Jane kidnapping Lorelei  and he is not strong enough to kill alone so i think it's Haffner