A person's handwriting may be authenticated by a lay witness -- i.e., a lay witness may identify the author of handwriting -- if the witness is personally familiar with the putative author's handwriting and the witness did not acquire such familiarity for purposes of the litigation.

United States v. McCellan, 868 F.2d 210, 214 (7th Cir. 1989) (upholding trial court's admission of the testimony of defendant's ex-wife from the 1986 adversary proceeding in bankruptcy because his ex-wife was unavailable....For purposes of the hearsay exceptions created by Federal Rule of Evidence 804 or a comparable State rule a declarant is "unavailable" within the meaning of Rule 804(b) or a comparable State rule if the declarant is unable to be present or to testify at the hearing because of death or then existing physical or mental illness or infirmity; but a declarant is not "unavailable" if the declarant's absence is due to the procurement or wrongdoing of the proponent of a statement for the purpose of preventing the witness from attending or testifying.

United States v. Schreane, 331 F.3d 548, 563-565 (6th Cir. 2003) (upholding trial court's ruling which allowed Officer Topping's testimony [about Duckett's statement during the stop] as an excited utterance because "Officer....A statement can qualify as an excited utterance for purposes of the hearsay exception created by by Federal Rule of Evidence 803(2) or a comparable State rule only if the declarant (the maker of the statement) personally perceived the exciting event or condition to which his or her statement relates.

Fed. R. Evid. 807.Statements that fall within an exception to the hearsay rule are admissible to prove the truth of the matter asserted by the declarant (the maker of the statement).