I just read about the story. It sounds reasonable to me.
There is lots of implied stuff but no direct or indirect evidence or charge of criminality. But could there be?

Heck yes there could be. I know what, why don't we appoint a special prosecutor to investigate. Of course, we want him independent, so there is no hint of political influence. Also, don't limit the scope of his inquiry--wouldn't want him to ignore potential leads into other charges. Finally, lets give him a huge budget so that he can hire a good staff of eager lawyers gunning to make a name for themselves.

I'll bet they'd come up with something plausible--if not on the direct charges than probably on something collateral like say, obstruction of justice against minor players.

Great idea, huh?