## Facts

- Carl S. Begay, an enrolled Indian living on a New Mexico reservation, was prosecuted in federal court for aggravated sexual abuse of an Indian child in Indian country under 18 U.S.C. §§ 1153, 2241(c), and 2245(2).
- Begay lived with his sister, his girlfriend (Anna R.), and Anna’s eight-year-old daughter (D.R.); Begay and D.R. sometimes slept in the same bed, usually with Anna between them.
- One evening in early December 1987, Anna slept separately due to menstruation, leaving D.R. in the bed with Begay; Anna turned on the light and observed Begay in shorts with D.R.’s pants unzipped and Begay holding D.R.
- D.R. testified that Begay undressed her, lay on her, and penetrated her vagina with his penis.
- A physician examined D.R. in March 1988 and observed an unusually large hymenal opening and an abrasion; the government relied on this as evidence of penetration.
- In May 1988, Begay confessed to federal investigators that he inserted his penis into D.R.’s vagina; the district court denied a motion to suppress the confession.
- Begay sought to introduce evidence that another man, John Jim, had previously raped D.R., including: (1) Jim’s guilty plea to aggravated sexual assault of D.R.; (2) D.R.’s statement to a defense investigator that Jim “gotten inside” her and Begay had not; and (3) anticipated medical testimony that it was impossible to determine whether Jim alone caused the hymenal irregularities.
- Begay moved to admit this evidence under Federal Rule of Evidence 412 to show an alternative source for physical findings and sexual knowledge; the district court excluded it under Rule 403 concerns (unfairness to the child, jury prejudice against the child, and confusion/mini-trial on Jim).
- During closing, the prosecution repeatedly argued that the medical evidence showed D.R. had been penetrated.
- The jury convicted Begay; he was sentenced to 108 months’ imprisonment and five years’ supervised release.

## Issues

1. Whether excluding evidence of the victim’s prior sexual abuse by another perpetrator—offered to show an alternative source of physical evidence—under Rules 412 and 403 violated the Sixth Amendment right to confront witnesses and present a defense.
2. Whether the district court committed sentencing errors under the Sentencing Guidelines (raised but not reached).

## Decision

- The Tenth Circuit reversed the conviction and remanded for a new trial.
- The court held that, on these facts, excluding the Jim-related evidence improperly restricted cross-examination and prevented Begay from presenting a meaningful alternative-source defense on the element of penetration.
- The court concluded the error was not harmless given the centrality of penetration to the charge and the government’s reliance on D.R.’s testimony and the medical findings.
- The court declined to address sentencing claims because reversal required a new trial.

## Legal Principles

- Federal Rule of Evidence 412 permits, in criminal cases, evidence of a victim’s other sexual behavior when offered to prove that someone other than the defendant was the source of semen, injury, or other physical evidence, and also when exclusion would violate the defendant’s constitutional rights.
- The Sixth Amendment Confrontation Clause and the right to present a defense can require admission of targeted evidence of prior sexual abuse by a known third party when it materially supports an alternative-perpetrator or alternative-source theory.
- Rule 403 balancing cannot be applied to exclude highly probative alternative-source evidence when doing so materially impairs the defense’s ability to contest an essential element (here, penetration) and to test the reliability of key prosecution proof.
- When the prosecution relies heavily on medical evidence to prove penetration, the defense must be permitted to present concrete evidence that the medical condition could be fully explained by another perpetrator’s admitted conduct.

## Conclusion

The Tenth Circuit ordered a new trial because the exclusion of evidence that a third party had previously raped the child—evidence directly bearing on the source of the medical findings and the penetration element—violated Begay’s Sixth Amendment rights and was not harmless in light of the government’s theory and proof at trial.


United States v. Begay, 937 F.2d 515 (10th Cir. 1991)