The prosecution must establish each essential element of a criminal offense beyond a reasonable doubt.

Abuan v. Level 3 Communications, Inc., 353 F.3d 1158, 1171 (10th Cir. 2003) (holding, in plaintiff employee's employment discrimination action against defendant employer, that the trial court properly admitted testimony of witness on....A statement by an agent or an employee who is not authorized to speak on behalf of the agent's principal or the employee's employer may nonetheless be treated as the statement of the principal or the employer and thus as a vicarious admission that is exempt from the prohibition against hearsay; but such a statement can be imputed to the principal or the employer only if the statement, if by an agent, is about a matter within the scope of the agent's agency or, if by an employee, the statement is about a matter within the scope of the employee's employment.

United States v. Butterworth, 511 F.3d 71, 74-75 (1st Cir. 2007) (upholding trial court's admission of grand jury testimony of defendant's girlfriend to cross-examine her after she gave testimony that was inconsistent with....A prior statement is exempt from the federal hearsay rule and is admissible to prove the truth of the matter asserted by the declarant with the prior statement if the prior statement was made under oath in another proceeding and if the prior statement is inconsistent with the declararant's testimony or with the admitted hearsay statement of the declarant.

Ingalls Shipbuilding Corp. v. Trehern, 155 F.2d 202, 203-204 (5th Cir. 1946) (holding, in plaintiff employee's personal injury action against defendant employer for failure to maintin a safe workplace, that witness's testimony about....Although Federal Rule of Evidence 411 bars the use of liability insurance or its absence on the issue of negligence or wrongful conduct, evidence about the existence or non-existence of liability insurance my be used to impeach a witness by showing the witness's bias or prejudice.