The fools!!! The media had this story on a glidepath to kill it within the next news cycle. But NO!! Kerry decides to goose it up for another couple of days by trying to make cheap and defensive political hay on the story!
Perhaps it was a "leak" in the sense that most people imagine what a leak is. But I doubt it.
Much more likely, Berger and his lawyers were getting out in front of a story they knew wouldn't be kept below the radar forever. In a town like DC, it's highly likely that at least one or two Dem-friendly reporters had been sitting on the story for months, but decided they couldn't sit on it any longer. So the Berger bunch jumped out with their statement.
Lacking further details, that's how I see it.