It wasn't red john who had the tattoo, that was probably one  of his assassins who did the killing like agent smith .she never said it was red john .Jane said that to Lisbon. red john is a master mind a man of art and mystery . he does things clean  not messy. the very same thing jane said to WALTER MASHBURN " you have a DIRTH PHOBIA" . think about it . WALTER also mentioned to Jane in that same episode "YOUR KNOW YOU DISSAPOINT ME" observe the manner and facial expression when he was telling him that as if its a teacher or parent speaking to a student/child. A BIG clue is that RJ always refer to Jane as Patrick he never calls him by "JANE". Every other person always call him JANE or MR JANE but not so WITH WALTER MASHBURN , he calls him by his first name ''PATRICK!"  jus AS RJ do. THAT  killing with the PI woman  was two messy to be RED JOHN , NO art and unfinished, "NOT clean at all" when red john does a murder he like it to be known (receive an audience ) and in a form of mystery ,it  must be a work well planned and well done . he likes art. A better suspect will be WALTER MASHBURN. 
                                              ALWAYS KEEP THAT IN MIND ABOUT  RJ