## Facts

- Frederick Bruce Walkey, Jr. lived with his wife, Alicia, and housemate Ellen Cosby, along with Cosby’s two-year-old son, Nathanel, for whom Walkey acted as a disciplinarian.
- On February 17, 1983, Nathanel was observed earlier in the day as playful and healthy; later that afternoon Cosby left Nathanel in the care of Walkey and Alicia.
- A visitor arrived around 6:30 p.m. and saw Walkey carrying Nathanel upstairs; the child was nonresponsive and limp, and Walkey appeared frightened.
- Two additional visitors arrived; Walkey later carried Nathanel out motionless and wrapped in blankets, went into the bathroom, and then had the visitors go outside.
- About 20 minutes later, the visitors were called inside because Nathanel was not breathing.
- Paramedics found Nathanel without pulse or respiration and observed extensive bruising and a distended abdomen; hospital staff noted additional injuries including bite marks and a fractured rib.
- A pathologist concluded Nathanel died from a severe penetrating abdominal blow that crushed and tore his intestines; the injuries were nonaccidental, with evidence of both old and recent trauma consistent with a battered child.
- Bite marks matched Walkey’s dental impressions; Walkey admitted biting Nathanel but denied beating him and claimed the child stopped breathing for unknown reasons.
- The prosecution presented expert testimony on “battering parent syndrome,” describing traits statistically associated with battering parents, including a history of childhood abuse; evidence showed Walkey had been physically abused as a child.

## Issues

1. Whether expert testimony on “battering parent syndrome” was admissible to assist the jury in a child-abuse homicide case or was impermissible profile/propensity evidence.
2. Whether the evidence was sufficient to support a first-degree murder conviction.
3. Whether admission of evidence of prior injuries and of Walkey’s childhood abuse was erroneous or unduly prejudicial.

## Decision

- The Court of Appeal affirmed the convictions for first-degree murder and child endangerment and affirmed the sentence (25 years to life; stayed term on endangerment).
- The court held the battering parent syndrome expert testimony was admissible and its admission was not an abuse of discretion.
- The court held substantial evidence supported the first-degree murder verdict.
- The court upheld admission of evidence of older injuries and Walkey’s childhood abuse as relevant and not unfairly prejudicial in context.

## Legal Principles

- Expert testimony is admissible when the subject is beyond common experience and the testimony would assist the trier of fact; the trial court has discretion under California evidence rules to admit such testimony.
- Syndrome-type testimony may be admissible in child-abuse prosecutions when used to explain patterns of nonaccidental injuries and abuse dynamics and when anchored to case-specific evidence, rather than offered as a standalone “profile” proving guilt.
- Evidence of prior injuries to the victim may be admitted to show a pattern of abuse and to address intent, identity, and absence of accident in a child-abuse homicide.
- Evidence bearing on characteristics referenced by an expert may be admitted when relevant to the expert’s explanation and the prosecution’s theory, so long as probative value is not substantially outweighed by unfair prejudice.

## Conclusion

The appellate court affirmed Walkey’s convictions, concluding that expert testimony about battering parent syndrome, together with medical and bite-mark evidence and Walkey’s custody of the child during the critical period, permissibly assisted the jury in evaluating nonaccidental injury, identity, and intent and supported the first-degree murder verdict.


People v. Walkey, 177 Cal. App. 3d 268, 223 Cal. Rptr. 132 (Cal. Ct. App. 1986)