The only entity which can provide such information with authority is Liberty Reserve itself.
AurumExchange, MtGox and Bitinstant, please, try to contact Liberty Reserve, in an official manner. If they don't respond, try to reach them via lawyers or something. I know it's possible that they'll just ignore the requests, but you'll never be sure if you don't try.
Unfortunately LR will not reply unless legal action is started, which is what we are also waiting for.
They've already said that explicitly to one of you?
I imagined that AurumExchange being an important client of Liberty Reserve, they would be OK with at least saying Yes or No to the "Did such transfer happen?" question.
Anyways... guess the way is to start a criminal complaint then.
It is not up to any of us to judge if funds should be unlocked, we should have an actual court with an actual judge do an actual investigation first.
Seriously, you 3 together have done a much better investigation than any "actual investigation" most official judges or police bureaus in the world would. The only think you lack is "authority".