What is an Affidavit of Heirship Document? This document is needed in situations where a Last Will and Testament had not been signed by a decedent prior to their death. It sets forth the status of the decedent’s family situation, so that a determination may be made as to the legal inheritor of the decedent’s assets according to application of the state statutes. It must be signed by at least two disinterested parties in front of a notary public and filed of record at the county courthouse.