Proof at trial involves and requires pretrial investigation and the pretrial preparation of evidence for possible trial.

United States v. Davis, 181 F.3d 147, 149 (D.C. Cir. 1999) (upholding trial court's admission of officer's redacted buy report as pretrial identification because in a case with similar facts, the court "affirmed the....A pretrial identification is exempt from the prohibition against hearsay evidence if the witness who made the identification testifies and is subject to cross-examination at the trial or hearing at which the identification is offered and if the witness who made the identification did so after perceiving the person whom he or she identified.

United States v. Milk, 447 F.3d 593, 600 (8th Cir. 2006) (upholding trial court's exclusion of evidence of victim's violent act because such violent act occurred five years earlier).Evidence that would be prohibited character evidence if offered to show a person's conduct is not barred by the character evidence rule if it is offered to show some other matter such as another person's belief.

United States v. Turning Bear, 357 F.3d 730, 733-734 (8th Cir. 2004) (conviction for aggravated sexual abuse of his son and daughter; accused challenged the trial court's exclusion of testimony from a foster care parent who saw the son on a daily basis for four to six months, and that in her opinion, the...Reputation or opinion is admissible to impeach a witness by showing the untruthfulness of the witness.