since opp has just sat down, he may not know that you have been out of line, and therefore probably doesnt know that he should be paying you off with marginal holdings, so a check behind on a very dry uncoordinated board isnt too bad, it lets him catch up a little.

I don't really understand why opp is check-raising the turn if you checked behind on the flop, so I would think maybe he picked up a flush draw on the turn and was going to let it check thru again, then decided to CR when you bet. That or he picked up 2 pr or had a hand already and is a perennial slowplayer.

Either way, a shove over the turn check-raise would seem to be best, as it doesn't look quite as strong as a pot committing/yet easier to call bet, and a draw that CRed will likely call the push anyways, as will the 2 pr hands, usually thinking you hit the K.