****** vehicle was recovered but sold again

my ****** vehicle was identified and with the police. We went to the premises where the person who bought the vehicle. explained to me he bought it with out the registration documents. I am the owner of the vehicle. the sap show him the case no but the procreass was still ongoing and at the.moment we didnt have a nr. Idrove to the police station and when we came back the vehicle was no longer found on the premises was gone. The person was aware that it was a ****** but Still he quickly sold it again my question is.what must I do now