I think Ellis Mars is Red John. Just a hunch. He played a serial killer in Cold Case ,i.e., George Marks.  He is under 6 ft (5' 10"). He is mar (if that was a real clue) could also be read as IIe is mar...which could be a reference to his true identity. Ellis Mars seems stupid but Lorelei says RJ is just like Jane. PJ deceived RJ in Season 4 finale...So RJ could haave done the same thing to PJ too.