Over the last few days, as we've been devoting a lot of coverage to the Bernard Madoff story, a number of readers have written in to say, "You're saying all this stuff about how he kept his scheme hidden. But you haven't been clear enough on what he actually did."

So let me try to clear this up, or explain why I don't think we really can clear it up yet.

The truth is that as yet we know very, very little about just what Madoff was doing or where the money went. One of the few official reports was in yesterday's statement from SEC Chairman Christopher Cox which noted that Madoff kept several sets of false books, etc. But that's hardly surprising.

Most of the assumptions stem from Madoff's own words describing it as a "Ponzi scheme" and his confession that he'd swindled some $50 billion. But calling something a Ponzi scheme covers a lot of territory. And it doesn't tell us that much in terms of where all the money went, whether it was a scam from the git-go or evolved into one, or much of any detail, etc.

I would also suggest one further note of caution, though this is much more speculative.

On its face Madoff is confessing to everything. He's saying he's a fraud and he swindled people out of $50 billion. So it's hard to see what he's holding back. That said, he appears to be maintaining the pretense that he managed the entire swindle on his own -- that none of the family members who were intimately involved in running the fraudulent part of his operation had any idea what he was doing. And that seems preposterous on its face.

It's understandable that he wouldn't want to pull his whole family down, and that his family wouldn't want to be pulled either. But I think it's worth keeping open the possibility that behind Madoff's maximal confession of guilt -- and in addition to wanting to protect his family -- there's more people he's trying to protect or secrets he's trying to hide.