(a) Criteria for Being Unavailable. A declarant is considered to be unavailable as a witness if the declarant:
(1) is exempted from testifying about the subject matter of the declarant's statement because the court rules that a privilege applies:
(2) refuses to testify about the subject matter despite a court order to do so;
(3) testifies to not remembering the subject matter;
(4) cannot be present or testify at the trial or hearing because of death or a then-existing infirmity, physical illness, or mental illness; or
(5) is absent from the trial or hearing and the statement's proponent has not been able, by process or other reasonable means, to procure:
(A) the declarant's attendance, in the case of a hearsay exc