i am sure that Robert krinkland is Red John and i become sure of that in tha last episode ( ep 16 in season 5 )
my Prove :
first robert laughs when patrick is about to see


Lorelei Martins

has been killed by red john you can see it again and assure
he banned patrick to ride the ambulance and caught him
his relation to betram to become sure he is out of any suspicious ?
second the director make him shakes hand with patrick obviously and no reasonable cause for shaking meaning ( not in a meating or introduction ,robert wants to shake hands with him especially ?????? )
  robert has a shot in a car Limousine just like luther being killed and Lorelei Martins was caught
third  his voice is very suspicious and look same in tha last episode in season 2 ???????? make a comparison and you can see the similarities

                           thanks ,