## Facts

- William Mark Mann was convicted of intentional child abuse resulting in death after his six-year-old son died from a screwdriver stab wound to the chest while staying at Mann’s home.
- Mann’s girlfriend (later wife), Patricia St. Jeor, awoke and observed Mann taking the child to the bathroom; she then heard a noise, a loud crash, and a scream.
- St. Jeor found the child on the bathroom floor appearing to seize; shortly after, she observed a screwdriver protruding from the child’s chest while Mann held or “cupped” it.
- St. Jeor, a nurse, attempted to help; Mann struck her and prevented paramedics from treating the child until law enforcement intervened.
- The child was transported to the hospital and died; medical personnel testified they did not disturb the screwdriver during resuscitation attempts.
- The State presented additional evidence of earlier skull and brain injuries inconsistent with Mann’s account of an accidental fall.
- The defense presented expert testimony that the screwdriver impalement could have been accidental.
- During deliberations, an engineer-juror applied engineering analysis to evaluate the defense theory and reported a very low probability of accidental impalement to other jurors.
- Jurors also discussed general experiences with children and medical professionals when evaluating credibility and plausibility.
- Mann moved for a new trial, asserting juror misconduct because the engineer’s calculations constituted extraneous evidence not admitted at trial.

## Issues

1. Whether a juror’s application of professional expertise (including calculations) during deliberations constitutes “extraneous prejudicial information” or an “outside influence” permitting impeachment of the verdict under Rule 11-606(B).
2. Whether juror discussions based on general life experiences improperly introduce extra-record information requiring a new trial.

## Decision

- The Supreme Court of New Mexico affirmed the conviction and the denial of a new trial.
- The court held the engineer-juror’s calculations reflected internal evaluation of the evidence, not extraneous information or an outside influence.
- The court held jurors’ reliance on general life experience in assessing testimony was permissible.
- Because the challenged conduct was internal to deliberations, juror affidavits could not be used to impeach the verdict under Rule 11-606(B).

## Legal Principles

- Rule 11-606(B) generally bars post-verdict inquiry into jury deliberations and mental processes, allowing juror impeachment only for (1) extraneous prejudicial information improperly brought to the jury’s attention or (2) outside influence improperly brought to bear on a juror.
- “Extraneous” information refers to information originating outside the trial record and outside the jurors themselves (e.g., media, third-party communications, independent investigation, or out-of-court experiments).
- Jurors may use common sense, background knowledge, education, and professional training to analyze and evaluate evidence admitted at trial.
- A juror’s technical reasoning, without an extra-record investigation or external source, is treated as internal deliberation rather than the introduction of new evidence.
- The Confrontation Clause is satisfied by the opportunity to confront witnesses in court; it does not require cross-examination of jurors’ internal reasoning during deliberations.

## Conclusion

The court held that jurors’ use of specialized training and ordinary life experience to assess trial evidence is part of protected internal deliberations and does not constitute extraneous information or outside influence; therefore, the verdict could not be impeached and Mann was not entitled to a new trial.


State v. Mann, 39 P.3d 124 (N.M. 2002)