Hello jjkaufmann2 and welcome to the Sailboat Owners' site,
Was the boat registered in your state? There appear to be shadows of registration numbers on the starboard bow. If it was registered numbers and letters and probably a registration sticker would have been on each side of the bow. The registration numbers and letters would not change as owners changed as long as the boat remained registered in the same state. There should also be paperwork with the boat verifying that registration. The previous owner may have that information.
Also, what year, make, and model did the seller say the boat was?
Best Wishes.