Here I am again folks, I was quite pleased that my theory of McAllister got so popular.
http://www.whoisredjohn.com/See-a-theory-Red-John/11543

And now I have found a good youtube video where Xander Berkeley is talking with a little high pitched voice. Enjoy with the comparison.

TAKE THAT!

Xander Berkeley starts at 1:25
https://www.youtube.com/watch?v=cZ5mLPZfMoQ

The Mentalist promo 6x08
https://www.youtube.com/watch?v=wrzRijdiKcM

Remember this is his normal voice, try to imagine when he makes an effort to make it a little higher. You even hear that little hoarse noise in his voice.