There have been hints that MtGox's losses were due exploitation of the transaction malleability issue. I don't know if it's possible to identify (from the bloc

There have been hints that MtGox's losses were due exploitation of the transaction malleability issue. I don't know if it's possible to identify (from the blockchain) transactions that have been altered in a way that exploits the malleability issue but it should certainly be possible to identify pairs of transactions with identical startpoints, endpoints and sizes (i.e. number of bitcoins). If it turned out that pairs of such transactions turned out to come from MtGox's wallets to third-party wallets, that would probably be a good starting point.