Here is my thoughts , here is my theory....
                     Please Read it...

  After the last episode , it's obvious 3 suspects had a tatoo on their left shoulder and the three are "good" whistlers ; those suspects are Gale Bertram , Reed smith and Sheriff Thomas Mccalister.
 
    We begin with Reed smith the unlikely suspect:
 - He is fat , doesn't fit any descriptions  and didn't appear in 4 first seasons, even if Bruno heller tries to make him suspicious, especially in the last episode but no way, he can't be RJ.
 
    And now Sheiff Thomas Mccalister is a good one , smarter. sometimes he appears alike Jane.

  The last One Gale Bertram he has many friends , he is a showman , Good posture , good speaker , high law enforcement.

   There are two things from the last episode that we should discuss it :
  
   1)  Gale Bertram after the discussion with Jane and Lisbon about closing in on Red John  , he makes a call, he said : " Yes, it's me , i had a very interesting discussion with patrick jane "

     =>  He calls a person who knows him , and who wants to keep informations about RJ. We don't know whom this guy. We should discuss that point.
.  
      2) Why Brett stiles cares when patrick wants to shoot Sheriff Thomas mccalister , and Stiles asks Patrick to see others two whom had the tatoo too :
     
     Did he want to protect Mccalister from shot , because he knew Sheriff is RJ , and patrick will shoot him 100% , because he waits 10 years for that moment.?
     OR
     Did he want to help Patrick , because he knew Mccalister is not Red john  and  Reed or Gale is the real RJ  ?
     OR
     Did he want patrick to know about the sign maybe of the organization "Tyger Tyger" , because Vizualize have some problem with them. ?

    Thanks to you all , don't forget to Share your points of view ...