Need to report fraudulent member

Long story short; I got into a recent transaction whereby I sold a design to a buyer worth $3** only after sending the goods I would find that the transaction and payment has been reversed due to fraudulent credit card use.

Also I contacted a member using the same username at NamePros who reported that his/her account at DP had been stolen and lost previously.

This member has obviously stolen both a DP user account and also credit card details, who do I report this member to so he is banned and/or the account returned to the rightful owner? I don't want this guy to be scamming other people again.

Thanks

MK