The exact addresses of the Gox stolen coins aren't known AFAIK. Even if they were, to cash out you only need to get someone to accept them without verifying ID. I can send coins to an exchange, and have them send me other coins in a different cryptocurrency, and send those to another exchange, then convert back to btc. If the intermediate currency is something like Monero, then the chain analysis must stop there.
I'm not saying most mixing happens through alts, but it is a fairly foolproof method for anonymity, at the cost of not supporting volume and high fees.
Also, you can sell to people for cash, so any investigation hits a dead end. There are probably dozens more ways to cash out anonymously.
It doesn't matter who keeps the logs, the blockchain is the log. I really think you are the one who is missing something. Because the blockchain has the entire history, everyone knows every transaction wallets X, Y, Z and any other wallet has ever done.
> A block chain is a transaction database shared by all nodes participating in a system based on the Bitcoin protocol. A full copy of a currency's block chain contains every transaction ever executed in the currency. With this information, one can find out how much value belonged to each address at any point in history.
You don't understand how mixing can work. I send money to your right pocket, you send me money back from your left pocket. At no point were your right and left pockets connected. As soon as you destroy your logs of what your pockets were, there's no way to identify which pocket was which.
Do you understand the concept of taint in block chain analysis, and how mixing can produce untainted coins?
>For these reasons, I cannot figure out why they don't know who stole the MtGox bitcoins.
When you don't understand something, something might be wrong with your model. (http://lesswrong.com/lw/if/your_strength_as_a_rationalist/ comes to mind).
The exact addresses of the Gox stolen coins aren't known AFAIK. Even if they were, to cash out you only need to get someone to accept them without verifying ID. I can send coins to an exchange, and have them send me other coins in a different cryptocurrency, and send those to another exchange, then convert back to btc. If the intermediate currency is something like Monero, then the chain analysis must stop there.
I'm not saying most mixing happens through alts, but it is a fairly foolproof method for anonymity, at the cost of not supporting volume and high fees.
Also, you can sell to people for cash, so any investigation hits a dead end. There are probably dozens more ways to cash out anonymously.