Only bad money managing from Gox
You could probably get a pretty good idea with careful examination of the blockchain, but you'd need Mt Gox's withdrawal records to be sure.. but the exact same amount withdrawn to the same address more than once, combined with hash padding issues seems like a good place to start.. Cross referenced with Mt Gox withdrawal records and their KYC records and it seems like you should be able to knock on someone's door and ask some good questions..
BTC withdrawals have been possible without the whole KYC-verification until not too long ago. If this problem has been going on for years as the leaked PDF claims, then it started way before Gox had names and other info on their BTC-withdrawers.