The rap on Roy Cooper (the North Carolina Attorney General) among my friends who know a good bit about him is that he is overcautious — a smart guy who is too often hesitant and a bit of a plodder. People I know who followed the investigation closely were confident that Cooper's investigators had concluded that the charges against the lacrosse players were without merit and that the lacrosse players were in fact innocent, but the betting money seemed to be that Cooper would issue a bland statement saying that there wasn't enough evidence to support a trial and leave it at that. That, after all, is the easy way out — the path of least resistance. He could have said that there was insufficient evidence, and that he would not go beyond that characterization because no further statement about the strength of the evidence was necessary for his decision. And I imagine that his political advisors probably told him that this would be the politically safe route to take (I can see counter-arguments, but my guess is that would have been their advice).
I find it remarkable, then, that he went so much further, saying that the accused players were in fact innocent, that there was no credible evidence against them, that the accuser's many different statements could not be rectified and that she contradicted herself, etc. This was not a garden-variety statement about insufficient evidence but instead was about as complete a vindication as the defendants could have imagined. Indeed, I think that Cooper said just about everything that the defendants could have wanted. Cooper must have really been convinced.
One final note: A defense lawyer (or a libertarian) treating this as a cautionary tale about the awesome power of a "rogue prosecutor" to run amok is not a surprise. But an attorney general framing the case that way is more striking. Not that Nifong didn't deserve this drubbing — just that I wasn't betting on it.