I am not sure why you would conduct this check on someone who has already played on your casino for significantly large amounts of funds before. I will wait and watch for the result in any case. I think your team should speed things up since this a half a million dollars on the line. It's not right to hold for this long.
I believe the 5 consecutive withdrawal of fund in different address triggers the security of thinking a possible hacking or money laundering. If the case is the prior then at least @OP is saved from losing another $500k, I don't think it is the latter but if ever it is, Duelbits had done a great job in preventing a person to launder money on their platform. And if the person is clean, Duelbits will release the fund as soon as they verify that there is no problem with the account. @OP just need a little patience since verification and investigation process takes time.