In my previous theory I chose Thomas because of the telephone conversation between him and PJ at episode 3 of season 6. He said "Hello Patrick" with the exact same manner and a somewhat lower voice like the Red John phonecall in episode 1. After the phonecall he sneaked upon PJ in the woods, PJ said "I didn't hear you coming.." Thomas replied with" I love to hunt things with faces".
Sounds like the m.o of Red John, everytime he leaves behind a face and the last time he painted the face on Teresa Lisbon face.
What I liked the most was in episode 6 when PJ brought all the suspects together, he asked everyone to lower their sleeves. The only one who got quite scared was Thomas. He immediately reacted with: "Patrick it's not what you think." Not because he is anxious about Patrick but more that he is going to lose his friend PJ now. Maybe Thomas somehow got into the TygerTyger group for resources.
