I accuse Bertram because description of Rosalind Harker and phcyho evaluation.
He camed in serie when Patrick started to come closer to the Red John.
He culd follow Patric whole time and he was the one who quouted Blakes poem.
He always asked wrong questions Patrick.
And at the end of seventh episode in sixth seasone he, reed and sheriff ware the only ones whit tattoos.
Reed Smith is just a deciple we know that for sure, sheriff climbed on the roof of the church so that kills the fear of heights clue. 
In moment when Patrick saw the tattoos, Bertram was only one who had look of guilt in he's eyes.

And just for everyone to know Bertram is my only suspec from the moment i saw him in The Mentalist.