I have read the majority of the media putting suspicion on the Ramseys.
As for co-operating, regardless of the Ramsey's innocence or guilt, generally speaking if you don't have a great alibi, and you are cliche suspect material (spouse, family member, neighbor, in the vicinity), you could be in big trouble. The Olympic Park bombing is a classic case. Richard Jewell couldn't have been any more accomodating to the authorities. And within a few days they were leaking to the press, and it was all over: Jewell, did it. I mean just look at the guy. He's weird. He's guilty...and so on and so forth. I'm sure the authorities have a bias to playing the percentages when looking at suspects. And once they get their hooks in, they are very determined and play hard, and they take a large proportion of the public with them. The only way they think you are co-operating is if you confess, and you can't do that if you are innocent. It destroyed Richard Jewell's life, anyway.