Well, you could look up the property records and try to find the address or description and see who owns it now for real estate tax purposes as that is public record. This could depend on what state it is. Also, if you want to learn more you can look up deed records in the county where the property is to research the "chain of title" to see if it was transferred or sold. There are title companies that will do this for you at a fee.
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Check the public records of the County Recorder and the Tax Assessor where the property is located. You may also check the records of the Probate Court of the County in which he lived to see how the property was transferred if he owned it at he time of his death. You may want to involve a Probate Attorney's office to help speed the Discovery. Good Luck !!
Check the land title records. Assuming the property is in Westchester near you, the County Clerk in White Plains would have land title records. If you don't know how to read indexes, a local title insurance agent could run a record title search for a fairly modest fee. Another option is to check your grandfather's payments over last few years to see if he is paying property tax, although that's not a sure thing. Also, the municipality tax office can advise whether there are tax bills in your grandfather's name, but that also isn't a sure thing because only the title records are official.
Lawrence Friedman, Bridgewater, NJ. Certified as an Elder Law Attorney by the ABA approved National Elder Law Foundation, former Chair NJ State Bar Association Elder and Disabilities Law Section, Member Board of Consultors of NJSBA Real Property, Trusts & Estates Law Section, Vice Chair Special Needs Law Section of National Academy of Elder Law Attorneys, and Master of Laws (L.L.M.) in Taxation from N.Y.U. School of Law. Visit SpecialNeedsNJ.com for articles and Q&A on elder law, special needs, wills, trusts, estates, and tax and SpecialNeedsNJ.com/blog for timely updates. Information on both Avvo and SpecialNeedsNJ.com does not constitute legal advice, as it is general in nature and may not apply to your situation or be subject to important changes. No attorney client relationship exists unless set forth in written engagement terms.