We quote below the pertinent portion of the appellate court's ruling: ⁷

While it is true that the affidavit was signed and subscribed before a notary public, the general rule is that affidavits are classified as hearsay evidence, unless affiants are placed on the witness stand (People's Bank and Trust Company vs. Leonidas, 207 SCRA 164). Affidavits are not considered the best evidence, if affiants are available as witnesses (Vallarta vs. Court of Appeals, 163 SCRA 587). The due execution of the affidavit was not sufficiently established. The notary public or others who saw that the document was signed or at least [could] confirm its recitals [were] not presented. There was no expert testimony or competent witness who attested to the genuineness of the questioned signatures. Worse, [respondent] denied the genuineness of her signature and that of her mother . . . [Respondent] testified that her mother was an illiterate and as far as she knew her mother could not write because she had not attended school (p. 7, ibid). Her testimony was corroborated by Ma. Sales Bolante Basa, who said the [respondent's] mother was illiterate.

The petitioners’ allegations are untenable. Before a private document offered as authentic can be received in evidence, its due execution and authenticity must be proved first. ⁸ And before a document is admitted as an exception to the hearsay rule under the Dead Man's Statute, the offeror must show (a) that the declarant is dead, insane or unable to testify; (b) that the declaration concerns a fact cognizable by the declarant; (c) that at the time the declaration was made, he was aware that the same was contrary to his interest; and (d) that circumstances render improbable the existence of any motive to falsify. ⁹

In this case, one of the affiants happens to be the respondent, who is still alive and who testified that the signature in the affidavit was not hers. A declaration against interest is not admissible if the declarant is available to testify as a witness. ¹⁰ Such declarant should be confronted with the statement against interest as a prior inconsistent statement.

The affidavit cannot be considered an ancient document either. An ancient document is one that is (1) more than 30 years old, (2) found in the proper custody, and (3) unblemished by any alteration or by any circumstance of suspicion. ¹¹ It must on its face appear to be genuine. The petitioners herein failed, however, to explain how the purported signature of Eduarda Apiado could have been affixed to the subject affidavit if, according to the witness, she was an illiterate woman who never had any formal schooling. This circumstance casts suspicion on its authenticity.

Not all notarized documents are exempted from the rule on authentication. Thus, an affidavit does not automatically become a public document just because it contains a notarial jurat. Furthermore, the affidavit in question does not state how the ownership of the subject land was transferred from Sinforoso Mendoza to Margarito Mendoza. By itself, an affidavit is not a mode of acquiring ownership.