It has been a matter of course recently to insist on having a notarized copy of a photo id of the Buyer and the Seller in order to complete a purchase. The deal shouldn't have closed without having all of the relevant paperwork/documentation in place.

You can likely get a court order for the Seller to be compelled to comply with providing the info as it is legally required to complete you registration - but that is going to take time and a lawyer.

Even if the Seller wasn't entirely happy with the deal, if he accepted it he is required to provide the necessary documentation to complete the transfer. If he doesn't then he continues to be the owner of record and in theory he continues to be liable for the property taxes and other outgoings/lawsuits/costs etc.