Evidence of a criminal or wrongful act apart from the act that at issue at trial Is not barred by the prohibition against circumstantial use of character if intent, knowledge, mistake, or accident is a legally-material factual issue, the opposing party suggests the non-existence of knowledge or urges mistake or accident as a defense, and evidence of another crime, wrong, or act is offered to prove the knowledge or the absence of mistake or accident by a criminal defendant or other person.

Fed. R. Evid. 104(a) advisory committee's note ("In some situations, the relevancy of an item of evidence, in the large sense, depends upon the existence of a particular preliminary fact. Thus when a spoken statement is relied upon to prove notice to X, it is without probative value unless X heard it. Or if a letter purporting to be from Y...A thing or matter is sufficiently authenticated to be admissible in evidence if the authenticating evidence submitted to the trial court is sufficient -- strong enough -- to permit a reasonable jury or reasonable trier of fact to conclude that the proffered thing or matter is authentic, that the proffered thing or matter is what its proponent claims it is.

United States v. Carson, 455 F.3d 336, 379-380 (D.C. Cir. 2006) (upholding trial court's refusal to admit the grand jury testimony of unavailable witnesses because "[defendants had] failed to show how the motive to develop....The hearsay exception for prior testimony applies in a criminal trial or proceeding only if the prior testimony was given against the person who is now the defendant in the criminal proceeding or trial.

United States v. Hunt, 521 F.3d 636, 643 (6th Cir. 2008) (upholding trial court's refusal to admit the statements from an affidavit under Rule 804(b)(1) because (1) "[defendant] has not demonstrated that the....The hearsay exception for prior testimony applies only if testimony was in fact previously given.