The death penalty shall also be imposed if the crime of rape is committed with any of the following aggravating/qualifying circumstances: 1) When the victim is under eighteen (18) years of age and the offender is a parent, ascendant, stepparent, guardian, relative by consanguinity or affinity within the third civil degree, or the common-law spouse of the parent of the victim; xxxx Both the RTC and the CA correctly ruled on the concurrence of the following elements of qualified rape, as defined in the aforequoted provisions of the RPC: (1) that the victim is a female over 12 years but under 18 years of age; (2) that the offender is a parent, ascendant, stepparent, guardian or relative by consanguinity or affinity within the third civil degree, or the common-law spouse of the parent of the victim; and (3) that the offender has carnal knowledge of the victim either through force, threat or intimidation; or when she is deprived of reason or is otherwise unconscious; or by means of fraudulent machinations or grave abuse of authority.10 The age of the victim at the time of the crime’s commission is undisputed. During the pre-trial, the parties agreed on the existence of AAA’s Certificate of Live Birth,11 a "certified true/xerox copy" of which forms part of the records and provides that AAA was born on October 10, 1990. AAA was then only 12 years old in December 2002, a significant fact that was sufficiently alleged in the Information. In People v. Pruna,12 we held that the best evidence to prove the age of the offended party is an original or certified true copy of the certificate of live birth of such party. As to the second element, there is no dispute that Colorado is a full-blood brother of AAA, as this was also among the parties’ stipulated facts during the case’s pre-trial. The grounds now being raised by Colorado to justify his exoneration delve mainly on the alleged absence of the crime’s third element. He denies AAA’s claim that he had ravished her, raising the defense of alibi and the alleged doubt and suspicion that should be ascribed to AAA’s accusations. On this matter, settled is the rule that the findings of the trial court on the credibility of a witness deserve great weight, given the clear advantage of a trial judge in the appreciation of testimonial evidence. We have repeatedly recognized that the trial court is in the best position to assess the credibility of witnesses and their testimonies, because of its unique opportunity to observe the witnesses first hand and to note their demeanor, conduct, and attitude under grueling examination. These are significant factors in evaluating the sincerity of witnesses, in the process of unearthing the truth. The rule finds even more stringent application where the said findings are sustained by the CA. Thus, except for compelling reasons, we are doctrinally bound by the trial court’s assessment of the credibility of witnesses.13 We then take due consideration of the trial court’s findings of fact, its assessment of AAA’s credibility, her testimony and the manner by which her statements were relayed, as discussed in the RTC’s Decision convicting Colorado and which reads in part: AAA testified directly and categorically how she was raped by the accused Neil Colorado who is her full-blood brother sometime in the night of December 2002. That while AAA was sleeping with her older brother BBB and her younger brother CCC, accused went near her and held her two (2) hands, covered her mouth with handkerchief. Thereafter, accused removed her short pants and underwear, and inserted his penis into her vagina. After removing his penis, accused went back to sleep.