## Facts

- Harold Arthur Henthorn’s second wife, Toni, died in September 2012 after falling more than 100 feet from a cliff in Rocky Mountain National Park during an anniversary hike.
- The fall occurred in a remote off-trail area with poor cellular service and no nearby aid stations.
- The government charged Henthorn with first-degree murder, alleging he acted with premeditation and malice aforethought by pushing Toni to her death.
- At trial, Henthorn argued Toni’s death was an accident.
- Over objection, the district court admitted evidence of two earlier incidents involving Henthorn and his wives: (1) the 1995 death of his first wife, Lynn, in an event treated at the time as an accident, and (2) a 2011 injury Toni sustained at the couple’s cabin.
- The district court admitted the prior-incident evidence under Federal Rule of Evidence 404(b) for limited purposes, including intent, plan, and lack of accident, and gave limiting instructions restricting the jury’s use of the evidence.
- Henthorn was convicted of first-degree murder in the District of Colorado and appealed, challenging the Rule 404(b) admission; appellate review was for abuse of discretion.

## Issues

1. Whether the district court abused its discretion by admitting evidence of the 1995 and 2011 incidents under Federal Rule of Evidence 404(b).
2. Whether the probative value of the prior-incident evidence was substantially outweighed by unfair prejudice under Federal Rule of Evidence 403.

## Decision

- The Tenth Circuit affirmed Henthorn’s conviction.
- The court held the district court did not abuse its discretion in admitting the prior-incident evidence under Rule 404(b).
- The court concluded the evidence was admitted for proper non-propensity purposes, was relevant to disputed issues (including lack of accident), and was not substantially outweighed by unfair prejudice under Rule 403.
- The court relied in part on the district court’s limiting instructions and the presumption that juries follow them.

## Legal Principles

- Rule 404(b) permits evidence of other acts for non-propensity purposes, including intent, motive, plan, and lack of accident.
- Other-acts evidence must be relevant to a material issue in dispute and must satisfy Rule 403 balancing; exclusion is required only when unfair prejudice substantially outweighs probative value.
- Similarity between prior incidents and the charged conduct can support relevance to intent and to rebut an accident defense.
- A district court’s Rule 404(b) and Rule 403 determinations are reviewed deferentially for abuse of discretion, and limiting instructions can reduce the risk of unfair prejudice.

## Conclusion

The Tenth Circuit upheld the admission of evidence about two prior incidents involving Henthorn’s wives because it was used to show intent, plan, and lack of accident rather than propensity, it was sufficiently probative given the contested accident theory, and the district court reasonably found its probative value was not substantially outweighed by unfair prejudice.


United States v. Henthorn, 864 F.3d 1241 (10th Cir. 2017)