Diamond Bar Caretaker Convicted of Strangling Two Elderly Women in His Care

A Los Angeles County jury has convicted a live-in overnight caretaker of murdering two elderly women he was supposed to be protecting at a small residential care home in Diamond Bar, delivering a guilty verdict that closes out a case rooted in one of the city's quietest suburban streets. Jianchun Li strangled 75-year-old Monica Moon Lee and 83-year-old Hee Sook Park inside the Happy Home Care For Elderly facility on Sapphire Canyon Road in June 2023, according to prosecutors.

The jury convicted Li on August 20, 2026 of two counts of first-degree murder with a special circumstance of multiple murders, and a week later, on August 27, rejected his insanity defense during the trial's sanity phase, according to the Los Angeles County District Attorney's Office. Both phases of the trial were held in Department P of Pomona Courthouse South, where Li is now scheduled to be sentenced on September 3, 2026. As reported by CBS Los Angeles, District Attorney Nathan Hochman said Li was “the person expected to keep the women safe.”

A Deadly Morning at a Six-Bed Care Home

Prosecutors say Li placed a plastic bag over Monica Moon Lee's head and wrapped electrical tape around her neck, strangling her after ushering her into a bathroom, per filings released by the District Attorney's Office. About 30 minutes later, he brought Hee Sook Park to the same restroom and killed her the same way, according to the same filings. Firefighters responded to the home shortly before 7 a.m. on June 24, 2023, but both women were pronounced dead at the scene.

The Los Angeles County Department of Medical Examiner-Coroner later determined that both women died from neck compression and suffocation just minutes apart, recording Lee's time of death at 8:45 a.m. and Park's at 8:54 a.m., the coroner's office found. That finding corrected early speculation in some initial media reports that the women had been shot, before officials confirmed the deaths resulted from manual suffocation and neck compression.

An Emergency Call and a Fast Arrest

Los Angeles County Sheriff's Department deputies were dispatched to the Sapphire Canyon Road residence around 8:07 a.m. that morning following an emergency call, and neighbors reported seeing caretakers exit the home with their hands raised on deputies' instructions before Li was taken into custody, according to SGV CityWatch. Li was formally booked into jail at 2:25 p.m. that same afternoon and was later held on $4 million bail. Lee, who used a walker, and Park were among six residents at the state-licensed facility, which has operated out of the four-bedroom suburban home since September 2017; four other elderly residents inside were left unharmed.

Li, who was 40 years old at the time of his arrest, worked as an overnight caretaker who lived on-site. According to CBS Los Angeles, District Attorney Hochman said the jury “held Li responsible” and found him sane, adding that the verdict could bring closure to the victims' loved ones and to the Diamond Bar community, and that Li “killed two vulnerable women entrusted to his care” and would “be held fully accountable.”

Hired Without a Background Check

Facility licensee Jung Hyun Kim hired Li on June 1, 2023 — just over three weeks before the killings — without completing the mandatory criminal history background check or exemption required under state regulations, a state administrative investigation disclosed, as reported by The Korea Daily. Li worked at least 15 days without background clearance while actively signing off on resident medication administration records, the outlet's report noted.

Following the killings, the California Department of Social Services assessed only a $500 administrative fine against Happy Home Care for allowing an unvetted employee to care for vulnerable residents without prior clearance, per the same account. The state permitted the home to keep operating and caring for its remaining residents while the agency conducted its regulatory review, the report added — a gap between state mandate and enforcement that underscores how heavily California's small residential care facilities for the elderly rely on licensee self-reporting until inspections, or tragedies, force a closer look.

What Comes Next

The prosecution was led by Deputy District Attorneys Michael Matoba and Stephanie Chavez of the District Attorney's Office's specialized Elder Abuse Section, which investigates and prosecutes physical violence, neglect, and financial exploitation involving senior citizens. Under California Penal Code Section 190.2(a)(3), Li's conviction on multiple-murder special circumstances carries a mandatory sentence of life in prison without the possibility of parole — the functional maximum penalty in California, which currently operates under a gubernatorial moratorium on executions. Li is set to be formally sentenced on September 3.