corrupt car dealer in Hamden ct

[waiting for justice]

My son traded a car in to auto exchange in hamden ct. The owners sister registered the new vehicle and said she was going to hand in the plates from the traded in vehicle while she was at DMV. well she didnt. And this is voer a year ago. My son is trying to register a car now and they say he owes over $1000.00 in taxes. My son went down to Auto exchange and tom the owner who says he isnt the owner anymore because he is being watched by the cops for drug dealing wont give him the plate or any paperwork. Is there anyhting we can do legally to this loser for stealing the plate? The hamden police know he is a known drug dealer and they told my son he probably kept the plate to drive to Ny to get his drugs. Please help