I think you are right on with that. The fact that he won't take it doesn't necessarily tell me that he did it, but that he might know a lot more than he is telling. I think it is very possible that if JW is going to tell the whole story of what happened that night he will have to mention some illegal activity by he and his friends. Possibly involvement in a drug deal or something of that nature. And in addition to admitting to his own illegal actions, he would likely have to rat out some of his friends. Maybe he is scared of what they will do to him if some of those "friends" are dangerous people. I don't think there is any legal way to force him to take it, but any half-decent human being would have to come clean at some point or their conscience would be eating them alive.
The way this case is turning out sort of reminds me of the Lauren Spierer case (still unsolved) at Indiana University. Multiple friends were with her the night she went missing, and it is widely assumed that at least one of them had something to do with it, but the friends have all lawyered up and many refused polygraphs. And since she was with so many friends the night she went missing (she is now presumed dead) they all have plausible deniability in that it could have been one of the others. There is very little evidence so as long as they don't say too much the police will not be able to pinpoint who is responsible. Her friends who are speaking out on her behalf say that they suspect drugs played a role that evening.
