AA in NL400 - Villain takes confusing line

[The Bear]

Party 400NL

Villain has 570. I have him covered. This is my first time playing with him. We've been together for a few hours and I haven't seen him get out of line.

He limps in MP, I raise to 15 in LP w/ A [img]/images/graemlins/diamond.gif[/img]A [img]/images/graemlins/club.gif[/img], he calls. Pot is 36.

Flop is 9 [img]/images/graemlins/heart.gif[/img]2 [img]/images/graemlins/club.gif[/img]8 [img]/images/graemlins/heart.gif[/img]

He checks, I bet 22, he raises to 74, I call. Pot is 184.

Turn is 8 [img]/images/graemlins/club.gif[/img]

He immediately checks. My default play is check it through here, but I thought I could confidently fold to a check-raise and considered JTh his most likely holding at this point.

So I bet $100. He thinks for about 15 seconds and calls. Pot is 384.

River is an offsuit 3 for a final board of 82983, with no 3-flush. He immediately pushes for his remaining 380.

I stare at my screen very confused. By the end of the turn, I was nearly certain that he had JTh, but this river bet (combined with the previous action) just screams 'MONSTER' from a tighty in that game.

Call or fold? Also, does anyone think betting the turn is really bad?

Thanks.

The Bear