Ray Haffner. 

In Red Barn, he shows up to try and give Lisbon a job- basically a dead giveaway that he wants to break up the Jane-Lisbon dream team. It's fairly obvious that he has a kind of fascination with Jane (he works with him in an earlier season) and has definitely shaken hands with him.

Add to that the fact that he's the right age, he was a member of Visualize at the right time and wouldn't admit to Lisbon whether he was on the Elliston Farm... yeah.