if it really is 45000 USD involved, surely this is worth getting the police involved rather than complaining about on a forum? surely without a police report for allegedly stolen 45000 its hard to take you seriously.
because the only proof is on scammer's database? not like bitcoin transfers are registered with taxman. also he stole only 4000 btc from me. many other had accounts there. even if money is recovered i can not prove it was mine without his database or wallet.db. so i already write off the money, but if this is nerd (and i suspect), i am glad he does not get to enjoy it. hope mtgox give it to EFF or torservers instead.
i wait for mtgox to explain, but i don't think many outside the forum have 45000btc. he also says already himself mtgox questions source of money.
Nevertheless, you can make a police report. Even if you don't expect the police to actually help you. (for example, when your passport or wallet is stolen in a random country when you're on holiday, and you want to get a new passport or claim on insurance).
Its in the very least a sign of sincerity: reluctance to even approach police about the issue is a fairly serious warning sign to me.