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(a) or a comparable State rule if the declarant testifies to a lack of memory of the subject matter of the declarant's statement; but a declarant is not "unavailable" if such claim of lack of memory is due to the procurement or wrongdoing of the proponent of a statement for the purpose of preventing the witness from attending or testifying.

General Eletric Co. v. Joiner, 522 U.S. 136, pin? (1997).It is primarily the responsibility and prerogative of the the trial court to determine whether evidence offered as scientific or expert evidence is sufficiently reliable to be admissible as scientific or expert evidence.

Fed. R. Evid. 901(b)(7) ("Evidence that a writing authorized by law to be recorded or filed and in fact recorded or filed in a public office, or a purported public record, report,....Federal Rule of Evidence 901(b)(7) and comparable State rules provide that a writing may be authenticated by evidence that the writing is authorized by law to be recorded or filed and is in fact recorded or filed in a public office; and a purported public record, report, statement, or data compilation, in any form, may be authenticated by evidence that it is from the public office where items of this nature are kept.

United States v. Anderson, 303 F.3d 847, 859 (7th Cir. 2002) (upholding trial court's admission of testimony about witnesses' statements to law enforcement officers which identified defendant as their drug supplier....A prior statement of a witness is exempt from the prohibition against hearsay evidence if the prior statement is consistent with the witness' testimony at the trial or hearing at which the prior statement is offered, the prior statement is offered to rebut a express or implied charge of recent fabrication or motive, and the witness who made the prior statement testifies and is subject to cross-examination at the trial or hearing at which the prior statement is offered.