Before going too far though you better consider whether you can force the seller to pay even with a court judgment (presumably small claims court). If their financial situation isn't good (e.g. this was a short sale) and/or all of their income is exempt (e.g. social security), collecting might be difficult or impossible and any time and money you spend will be wasted. On the other hand, if the real estate attorney has some way of keeping the county from reassessing after the sale, that would avoid the collection problem.
I would call the Escrow company tomorrow morning first thing. They are responsible to inquire and verify all the facts of the previous ownerâ€™s situation. They are your allies in this right now and the best place to start.