A Riverside County Superior Court judge has ruled that an Eastvale mother must stand trial for first-degree murder in the October 2022 death of her 2-year-old son, nearly four years after paramedics attempted to resuscitate the toddler at the family's home. Judge Timothy Freer determined there was sufficient evidence to bind 35-year-old Xiu Xiu Sun over on charges of murder and assault on a child resulting in great bodily injury or death.
Sun is accused of killing her son, Chris Cui, at the family's Eastvale residence, according to MyNewsLA.com. Riverside County Sheriff's Sgt. Steve Brosche said patrol deputies were called to the 6000 block of Rosewood Way near Turnberry Place in Eastvale on the morning of October 20, 2022, after reports of an injured child. First responders arrived around 9 a.m. to find paramedics attempting to resuscitate Chris, who was pronounced dead at the scene.
Foul play was suspected in the toddler's death, and central homicide unit detectives took over the investigation from patrol deputies, questioning both Sun and her husband. According to Brosche, Sun's husband was allowed to leave the sheriff's Jurupa Valley Station without suspicion of involvement, while Sun was taken into custody there without incident. Investigators have released no details regarding the circumstances of the fatality or a possible motive.
A Case Frozen for Years by Mental Competency Proceedings
The nearly four-year gap between Sun's arrest and this month's ruling stems from California's competency restoration process. Shortly after her October 2022 arrest, Sun's public defender submitted motions arguing she was psychologically unstable and required mental health treatment, and Superior Court Judge Gail O'Rane granted a formal psychological evaluation, according to Patch. Psychiatric evaluations continued through most of 2023, and the judge ultimately ruled that Sun should undergo mental health treatment, resulting in her commitment to a state hospital.
Under California law, criminal proceedings can be suspended when a defendant is declared mentally incompetent, requiring competency restoration before a case can move forward, per Eisner Gorin LLP. That framework is why Sun's case sat dormant for roughly two years. According to the district attorney's office, a judge determined in late 2024 that her mental competency had been restored, clearing the way for the case to resume.
Court proceedings subsequently resumed. Riverside County Superior Court subsequently held a preliminary hearing for Sun, culminating in Judge Freer's ruling this month that she must stand trial on both felony counts. A post-preliminary hearing arraignment has been scheduled for September 10 at the Riverside Hall of Justice.
Detention, Bail, and the Road Ahead
Sun is currently held on $1 million bail at the Robert Presley Detention Center, according to Greg Hill & Associates. The article notes Sun has no documented prior felony convictions in Riverside County. It remains unclear from court filings what specific injuries caused Chris Cui's death or what, if any, motive prosecutors will present at trial.
The competency restoration that froze Sun's case for two years is legally distinct from any insanity defense tied to her mental state at the time of the alleged offense, a separate legal question that may surface as the case heads toward trial. The child-assault charge is one of the felony counts in the case.
Eastvale's Contract Police and the Broader Numbers
Eastvale does not operate its own municipal police department; law enforcement in the city is provided under contract by the Riverside County Sheriff's Office out of its Jurupa Valley Station, according to the Riverside County Sheriff's Department. Eastvale incorporated as the county's 27th city in October 2010, growing from rural dairy farmland into a suburban city of nearly 70,000 residents with a median household income exceeding $150,000.
The article does not provide statewide child-fatality figures for comparison. Separately, the article does not provide statewide child-homicide rate comparisons.
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