A judge Wednesday ordered a woman accused of killing her 2-year-old son in Eastvale to undergo psychiatric evaluations to determine whether she's mentally competent.
Xiu Xiu Sun, 31, was arrested Thursday following a Riverside County Sheriff's Department investigation into the death of Chris Cui.
Sun is charged with murder and assault on a child resulting in great bodily injury or death.
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She was slated to be arraigned Wednesday at the Riverside Hall of Justice, but during the hearing, her public defender submitted a request to Superior Court Judge Gail O'Rane asking for an assessment of the defendant's mental state.
O'Rane suspended further criminal proceedings pending mental health exams.
Sun remains held without bail at the Robert Presley Jail in Riverside.
According to sheriff's Sgt. Steve Brosche, patrol deputies were called to the defendant's and her husband's residence in the 6000 block of Rosewood Way, near Turnberry Place, about 9 a.m. Thursday to investigate reports of an injured child.
Brosche said that deputies arrived to find paramedics trying to resuscitate Chris, who had suffered unspecified injuries.
"After life-saving measures were unsuccessful, the juvenile was pronounced dead at the scene,'' Brosche said. "During the course of the investigation, foul play was suspected surrounding the juvenile's death.''
He said that Central Homicide Unit detectives took over the investigation, questioning both Sun and her spouse, whose identity was not released.
Sun was taken into custody without incident Thursday evening at the sheriff's Jurupa Valley station, and her husband was allowed to leave, without suspicion of involvement in the toddler's death, according to Brosche.
Details regarding the circumstances behind the fatality, including a possible motive, were not released.
Sun has no documented prior felony convictions in Riverside County.