I personally think it's Reede Smith. I know he isn't exactly everyone's guess because of his looks and age in 1988, but in 1988 Red John only killed 2 people. It wasn't another 10 years until it started again. That means he would have been 22 In 1998.
My main point is that if you remember RJ holds his cup left handed, if you go to Lisbon's dream, you can see Smith holding his blade with his left hand. When RJ saves PJ you can see easily that he wipes his blade off with his right hand, indicating he is holding it left handed.
In Lisbon's dream, Haffner is the last one they show, but he is holding his blade right handed, then slices Lisbon's neck with his knife in his right hand.
So is it possible that RJ is left handed only? You can go to where RJ is painting on Lisbon's face, it's hard to tell but he is drawing it with his left hand, but when he wipes the blade it's with the left hand, so could this show that it isn't red john who wiped the blade?
