You clearly misunderstand how the mtgox hist, or nohist happened, and have no idea of how money laundering would work. Two years ago, or however long ago it took for someone to figure out they could do a double withdrawal, when they started skimming off the transaction you'd get one request to one public address. That transaction failed, and unless mtgox kept a detailed report of which transactions failed even they wouldn't know that those were the coins that were stolen. Now lets say they figure it out eventually, but right now they mostly know that they have a balance in their wallet that doesn't match the balance on their books. The problem is then that the coins were most likely laundered. Just have to go and buy some stuff with the bitcoins, and then resell that stuff ether for new bitcoins and at an entirely different public address, or for cash. The dirty bitcoins are still dirty, but the criminal has clean bitcoins and clean cash. The only punishment that could be handed out at that point is to punish the unwitting launderer who isn't the actual criminal. The same exact thing happens with dirty money. It's why money laundering and shadow banking exist, and is in part why cash has serial numbers on it. The goal of the money launderer is to get those bitcoins spent as quickly and by as many real people as possible. Gambling would be a good place to launder 'coins. It gets them trading hands so quickly that by the time anyone would have flagged the coins as stolen the crooks have nearly untraceable versions in exchange.