I've been in a similar Situation re: co-worker who was found guilty of Research fraud by the ORI.
When I did find out, I didn't do anything about it. Why? It's not my Job to intefere with people's personal affairs. And I don't care how much of a grade A Piece of work he was, its not my Job and interest, nor should it be yours. This is an HR issue and unless you see something that is directly related to those Actions (fraud) he committed and you can be directly or directly impacted by it, then table it! Your complaints are about his Management style. That's a separate issue, respond to that.
Now others will say it is your Moral and ethical responsiblity to blah blah blah blah blah, horsepoo, horsepoo. Unless you are Aware that there is similar behavior going on with confirmed evidence, then i advise you stay silent, do you Job and manage the way you would manage without this Piece of Information. Unless you have current evidence that this behavior is going on today in your Company, then the only one who will lose...is you!!!
Avoid entagling relationships with HR and Management that, in the end, will negatively Impact you.
As far as Steven Z's last comment about wanted to work for a smaller Company - due to what i interprate as his perceived better morals and ethics....ha ha..ha...ha....thanks for the laugh. Seriously? (i've been in both big and small companies).
I hear your Points and I don't negate validity there..but...I'm with Dave he summed it up nicely. We can go in endless discussion here that's not relevant to the Forum.