It's Haffner. He is agile, charming, fits the physical description etc but the most important clue is that RJ left Lisbon alive. WHY would he leave her alive? Because he cares about her, as he told her in the hospital. He is Red John and Stiles is his father. Kirkland was either Lorelei's sister's boyfriend and is out for his own revenge, or he is RJ's right hand man.

No idea what that meeting between Bertram, Mcallister and Steele was about though.