FACTS:

This case involves a dispute over a Deed of Absolute Sale allegedly executed by the sisters Rufina Casimiro (seller) and Rafaela Casimiro (buyer). The two sisters co-owned two parcels of land. When the petitioners discovered that the properties had allegedly been sold by Rufina to Rafaela, they filed a complaint for recovery of real property with damages. The trial court ruled in favor of the petitioners, finding the Deed of Absolute Sale to be a forgery.

The Regional Trial Court declared the thumbmarks as forged and null and void, while the Court of Appeals reversed this ruling. The petitioners filed a petition for review before the Supreme Court, arguing that the Court of Appeals erred in reversing the trial court's ruling. The Supreme Court concluded that the purported thumbmarks were false and merely simulated to make it appear that Rufina had consented to the alleged sale.

The petitioners successfully discharged the burden of proving that the thumbmarks on the document are false and simulated by presenting an expert witness who contrasted the thumbmarks on the document with specimen thumbmarks on authentic documents. The respondents relied on the disputable presumption of regularity and the testimony of the notary public who notarized the document. The court emphasized the importance of expert witnesses in determining fundamental differences in writing characteristics in the examination of forged documents.

This case also involves the credibility and probative value of expert opinions. The court emphasizes that the probative force of an expert's testimony lies not only in the statement of their theory or opinion but also in the facts and reasons upon which their conclusion is founded. The witness rendering an opinion must be credible and possess the necessary qualifications and knowledge on the subject matter. The court rejects dismissiveness towards an expert witness and notes that performing specific tasks, such as taking fingerprints, does not discount competence. The expert in question personally scrutinized and compared disputed thumbmarks, detailing his findings in reports and testifying before the trial court.

ISSUES:

1. Whether the testimony of a fingerprint expert is admissible as expert opinion.

2. Whether the testimony of the fingerprint expert is credible.

3. Whether the thumbmarks appearing on the Deed of Absolute Sale belong to Rufina Casimiro.

4. Whether the comparison of the thumbmarks on the Deed of Absolute Sale with the standard thumbmarks is sufficient to establish forgery.

5. Whether or not the thumbmarks appearing on the Deed of Absolute Sale were genuine.

6. Whether or not the testimony of the notary public who notarized the Deed of Absolute Sale can be given credence.

RULING:

1. The testimony of a fingerprint expert is admissible as expert opinion. The expert is allowed to give an opinion on matters which are within his knowledge or with which he has sufficient familiarity.

2. The testimony of the fingerprint expert is credible. The expert personally scrutinized and compared the thumbprints in question, detailed his findings in his report, and clarified any potential conflicts between his reports. The court relied on the expert's examination to determine the genuineness of the thumbprints and found his testimony to be straightforward and consistent, bearing the earmarks of credibility.

3. The thumbmarks appearing on the Deed of Absolute Sale do not belong to Rufina Casimiro. The Regional Trial Court judge and the NBI expert both concluded that the thumbmarks on the Deed of Absolute Sale were of the "circle type" while the genuine thumbmarks of Rufina Casimiro were of the "loop type." Additionally, the NBI expert's Technical Investigation/Identification Report explicitly stated that the questioned thumbmarks were not identical to the standard thumbmarks.

4. The comparison of the thumbmarks on the Deed of Absolute Sale with the standard thumbmarks is sufficient to establish forgery. The NBI expert confirmed that all the requisites for comparison, including fingerprint patterns, flow of ridges, and location and relationship of characteristics, had been satisfied. The faint and blurred features of the thumbmarks on the standard documents did not prevent positive identification and were still suitable for comparison. The Court of Appeals erred in disregarding this reasoning.

5. The thumbmarks appearing on the Deed of Absolute Sale were found to be not genuine and were proven to be different from the thumbmarks appearing on authentic, standard documents.

6. The testimony of the notary public was not given credence due to his questionable credibility, as evidenced by his admission of notarizing an affidavit which contained false entries.

PRINCIPLES:

• An expert witness may provide an opinion based on specialized knowledge, skill, experience, or training.

• Expert opinion must be supported by sufficient familiarity with the subject matter.

• The testimony of an expert witness must be credible in itself, conforming to common experience and observation, and in accordance with the knowledge, observation, and experience of mankind.

• The credibility of an expert witness is determined by his or her possession of knowledge, skill, experience, or training on the subject matter of his or her testimony.

• The Frye standard requires general acceptance of a scientific principle or discovery in the particular field to which it belongs.

• The Daubert standard allows for a more flexible approach, wherein the judge acts as a "gatekeeper" to determine the admissibility of expert scientific testimony.

• The admissibility of scientific evidence should be determined by the judge based on whether the offered testimony is scientific knowledge and whether it will assist the trier of fact in understanding or determining a fact in issue.

• The standards for determining the admissibility of scientific evidence include: whether the theory or technique in question can be tested and has been tested, whether it has been subjected to peer review and publication, its known or potential error rate, the existence and maintenance of standards controlling its operation, and whether it has attracted widespread acceptance within a relevant scientific community.

• The inquiry is flexible and the focus should be on principles and methodology, not on the conclusions generated. The judge should also be mindful of other applicable rules.

• A comparison based on a mere xerox copy or reproduction of the document under controversy cannot produce reliable results.

• Judges exercise independent judgment in appraising the authenticity of a signature or fingerprint.

• All the requisites for comparing thumbmarks, including fingerprint patterns, flow of ridges, and location and relationship of characteristics, must be satisfied.

• The faint and blurred features of thumbmarks on standard documents do not prevent positive identification and are still suitable for comparison.

• The presumption of regularity in the execution of notarial documents does not apply when there are doubts regarding the credibility of the notary public.

• Clear and convincing evidence must be presented to prove forgery. Testimonial evidence cannot prevail over physical facts.

• The general presumption that notarized documents were duly executed can be overcome by more compelling evidence presented by the party alleging forgery.