How do I determine who the executor of my grandfather's estate is/was? Is it possible there isn't/wasn't one?

I recently searched for unclaimed funds on the NY state website and found a result for my grandfather. I explained this to my aging father who is not computer savvy, doesn't own a computer or a cell phone, and who has difficulty with complex tasks. He has asked me to attempt to claim the funds for him. From my understanding of the documentation needed i would need to prove lineage which would require documentation I am not privileged to. Additionally, Ive come to understand that even if I had the documentation required NY State would only release the unclaimed funds to the executor of my grandfather's estate. I attempted to determine who that is/was by contacting the county court system where my grandfather lived. I was told that there was nothing in their system with his name. My father was not the executor of my grandfather's estate. It's possible it was his sister who is estranged from the rest of the family. I'm just not sure what to do next.