I don't think that this person is part of an organized terror group. He is probably just an American nutcase--like Timothy McVeigh or the Unabomber. He's probably very, very smart and nothing about him screams that he is a loony.
I don't think he lives secretively. We're not a very neighborly bunch anymore--I mean, do you know when your neighbors come home or what type of work that they do? Odds are that you don't. No one pays attention to anyone else any more (of course, I'm not talking about small-town life but urban and suburban).
Think about this. All he has to do is simply stop. No more clues, no more chances to get caught or simply slip up. Just resume your daily life--because I don't think that the police have enough to catch him yet.
Each of us is a special creature, unlike any other. And yet we are all alike.