It's ALEX JANE.
Patrick Jane's father.

Nobody else knows Patrick better than him.
Alex taught all he knew about about being a mentalist/psychic, when they were living together 24x7 in the fair, carnival lifestyle.

Alex is very good manipulating minds, with no regrets and no feelings.
Actually he has no feelings for his own son Patrick neither!.
His father is also known to be very focused in getting money and spending it gambling or playing poker. In example, the night they sell the cristal/mineral to the dying young girl at the fair in the tent. This is a psyco mind profile, no empathy or feelings for a dying child that needs real help.

As long as Patrick abandoned the carnival, and he was key part of the mentalist show at the fair, his father lost a very important part of his way of life to get money.
So, in a way, Patrick took/stole to his father what he most loved or needed.

In revenge, Alex Jane took what Patrick most loved: HIS FAMILY.
(Actually, Patrick Jane's wife was living in the fair too, and abandoned the carnival with Patrick.)

After some years of Patrick abandoning the fair, Alex saw his very own son to be a mentalist of success (making money!) on TV shows using his father's skills, tricks and knowledge about being a mentalist.
In short, Patrick used the training of his own father after abandoning him, doing precisely what Patrick renounced to: stealing money from innocent people.

All of this long story between Red John and Patrick is like a test built by his own father to demonstrate that Patrick is not as smart or clever as his father.
Is a pulse fight between them two.

All people Red John uses to kill people or trick Jane, are people that lost something important in their lives, so they are vulnerable or easy-to-manipulate for a professional mentalist like Alex Jane.

It's not yet supported, but maybe Alex killed his wife too; in other words: Patrick's mother.
Alex is a bad person, apart from a bad father.

DAMN CLEAR.