In this case, you do not need a consulting firm or any third party if you are not able to prove the source of the deposit funds, especially if you intend to withdraw a large amount. Any third party consultant will not be able to provide you with support in this case or if the casino is planning to scam your winnings in any available way.

Personally, this is the first time I have come across a case where the source of the deposit funds was asked, and I expected that this could only be done through questioning by the legal authorities, otherwise there would be no good reason for the casino to suspect the source of your funds.

My advice to you is to tell us the name of the casino and if you are one of the lucky ones, it may be one of the casinos that has a representation here on the forum so that we can communicate with the team. This will make it easier for us to verify the reputation of the casino and know the type of evidence required. In general, it would be better if you were able to provide clear evidence of the source of your funds because there is not much that can be done.