P.R. Laws Ap. tit. 32A, § IV, Rule 64
(A) Definition. — “Unavailability as a witness” includes situations in which the declarant:
(1) Is exempted or unable to testify because of a privilege acknowledged by this rule concerning the subject matter of his statement; or
(2) persists in refusing to testify despite an order of the court to do so; or
(3) testifies to a lack of memory; or
(4) has died or is unable to be present and testify because of a physical or mental illness or infirmity; or
(5) is absent from the hearing and the proponent of his statement has exercised reasonable diligence to procure his attendance by a summons of the court.
A declarant is not unavailable as a witness if the reason alleged for the unavailability is that the procurement or conduct of the proponent of his statement has been such as to prevent the witness from appearing or testifying.
(B) When the declarant is unavailable as a witness, the following exceptions to the hearsay rule are admissible:
(1) Former testimony. — Testimony given as a witness at another hearing, or a deposition taken in compliance with the law in the course of the same or another proceeding, if the party against whom the testimony was given offered it for his own benefit or had the opportunity to cross-examine the declarant with an interest or motive similar to that had in the hearing.
(2) Statement under belief of impending death. — A statement made by a person according to his personal knowledge and while believing that his death is imminent.
(3) Statement against interest. — A statement which, at the time of its making, was so far contrary to the declarant’s pecuniary or proprietary interests, or so far tended to subject him to civil or criminal liability, or to render invalid a claim by him against another, or to create a risk of turning him into the object of hatred, ridicule or social misfortune, that a reasonable man in his position would not have made the statement unless he believed it to be true.
(4) Statement of personal or family history. —
(i) A statement concerning the declarant’s own birth, adoption, marriage, divorce, legitimacy, relationship by blood or marriage, race, ancestry or other similar fact of his personal or family history, even though the declarant had no means of acquiring personal knowledge of the matter stated.
(ii) A statement concerning the matters set forth in subdivision (i) above, and death also, of another person, if the declarant was related to the other by blood, marriage or adoption, or was so intimately associated with the other’s family as to be likely to have accurate information concerning the matter declared.
(5) Other exceptions. — A statement having circumstantial guarantees of trustworthiness, if it is determined that:
(i) the statement is more probative on the point for which it is offered than any other evidence which the proponent may procure through reasonable efforts, and
(ii) the proponent notified the adverse party sufficiently in advance his intention to offer the statement, and the particulars of it, including the name and address of the declarant.