People have tracked the addresses where an entity (very likely to be MtGox) transferred funds to prove that they had lots of bitcoins, and they haven't been moved from that address since then.
If insider “malfeasance” is the true cause, it just boils down to “who is more patient, those who have lost some funds, or the guy sitting on 700,000 BTC and just needs to wait for this to blow over”?
