Suspect: Patrick Jane's father (played by Nick Chinlund)

Reasons:

He is the only one who could know that Eileen was a childhood memory for Patrick (this to me is the most critical clue)
He was a conman who taught Patrick how to think like one, and can thus get into his mind
He may have hated Patrick for abandoning him and would resent his new family enough to deprive him. Also, explains RJ's obsession with Patrick


Against:

Not on the list- but the list could be a red herring despite Heller's insistence (similar to Brad Whitfield masquerading as RJ)
Too old- would be in his 60s (but so is Stiles)