The 2023 deaths of two elderly care-home residents led to murder charges, a sanity trial and permanent imprisonment.
DIAMOND BAR, Calif. — When deputies entered a residential care home here on the morning of June 24, 2023, much of what had happened was still unknown. Two elderly women were dead, a caretaker was being detained and investigators had not yet publicly explained how the residents had been killed.
More than three years later, the uncertainty that surrounded those first hours has been replaced by a jury verdict and a final trial-court sentence. Jianchun Li, 44, was convicted of first-degree murder in the deaths of Monica Moon Lee, 75, and Hee Sook Park, 83, found legally sane at the time of the crimes and sentenced to two consecutive terms of life in prison without the possibility of parole. The outcome followed a case that moved from a neighborhood homicide investigation to a two-stage jury trial in Pomona.
The first public reports on June 24 were limited and sometimes contradictory. Deputies and emergency crews had responded to the Happy Home Care for Elderly property on Sapphire Canyon Road around 8 a.m. Early reports circulating that day described a shooting, but Los Angeles County sheriff’s officials said the women had not been shot. Both residents were pronounced dead despite efforts by paramedics. Investigators described foul play but initially withheld the cause and manner of the deaths while detectives worked at the home.
Li, who worked as a live-in or overnight caretaker, was arrested later that afternoon. He was 40 at the time and was initially held in lieu of $4 million bail. The scene stood out in a quiet residential area because the facility operated from a suburban house rather than a large medical campus. Reports based on state records said the licensed home could accommodate up to six residents. Authorities said four other residents were not harmed, and sheriff’s officials said there was no continuing danger to the surrounding community.
Within days, prosecutors charged Li with two counts of murder. Lee and Park had been publicly identified, but much of the evidence that would later define the case was still not known outside the investigation. California’s Department of Social Services also opened an investigation into the care facility after the deaths. At that stage, the prosecution was only beginning, and news reports appropriately described the allegations as unproven charges against Li.
The later trial record supplied the sequence that early reports lacked. Prosecutors said Li was working an overnight shift when, shortly before 7 a.m., he brought Lee into a bathroom. Lee used a walker and was dependent on the care environment for assistance. Li killed her by asphyxiation using a plastic bag secured with electrical tape, according to prosecutors. About 30 minutes later, he took Park into the same bathroom and killed her using the same method.
The investigation also produced evidence of Li’s own conduct after the killings. A prosecution trial filing cited in reporting on the sentencing said he called 911 and admitted that he had killed people. Prosecutors said he later made a similar admission when a nurse reached the home. Detectives searching his phone found internet queries involving choking, California’s punishment for murder and whether first-degree murderers could receive treatment for illnesses, according to the filing. Those details were eventually placed before the court as prosecutors built the case beyond the basic fact that the women had died while Li was on duty.
The case then spent years moving toward trial. The District Attorney’s Office assigned it to its Elder Abuse Section, and Deputy District Attorneys Michael Matoba and Stephanie Chavez handled the prosecution. The Los Angeles County Sheriff’s Department was responsible for the homicide investigation. The case carried the number KA133243 in Pomona court. During that period, Li remained the defendant in a pending criminal prosecution; guilt was not established until a jury returned its verdicts in August 2026.
On Aug. 20, jurors found Li guilty of two counts of first-degree murder. They also found true a special circumstance alleging multiple murders, a finding that made life imprisonment without parole available. But that did not finish the trial because Li had entered a plea of not guilty by reason of insanity. The jury therefore moved to a separate sanity phase to decide his legal mental state at the time he killed Lee and Park.
That second decision came Aug. 27. Jurors rejected the insanity defense and found Li legally sane. Evidence later discussed at sentencing showed the defense had presented circumstances including depression, excessive workload and Li’s struggles as a recent immigrant. The jury’s ruling did not necessarily deny the existence of those difficulties; it rejected the legal claim that insanity excused him from criminal responsibility for the murders.
The case reached its final major trial-court stage on Sept. 3. Defense attorney Ivonne De La Cruz asked Superior Court Judge Mike Camacho for a new trial on the sanity issue. She argued that questioning by Camacho during testimony from a defense expert had substantially undermined that witness’s evidence. The judge denied the motion, saying in substance that the jury’s result would have been unchanged, and described the evidence of Li’s guilt as overwhelming.
Camacho also emphasized the relationship between Li and the women. He had knowingly taken on a duty to care for Lee and Park, the judge said. That point connected the sentencing hearing to circumstances that had been present from the first day of the investigation but were not initially understood in full: the person arrested at the home was not a stranger who had entered the property. He was a caregiver working the overnight shift where the two victims lived.
The women’s relatives then described what the three-year criminal timeline meant outside court filings. Robert Lee told the judge about receiving the call that led him to learn of his mother’s death and said he had believed she was in a safe place. Yun Park said his mother had entered the facility because she required more care around the clock. She had been there for only about a month before the killing, he told the court.
Camacho sentenced Li to life without the possibility of parole for each first-degree murder and ordered the terms to run consecutively. Los Angeles County District Attorney Nathan Hochman said the jury had held Li responsible for killing two vulnerable women entrusted to his care and expressed hope that the verdict would provide some measure of closure to the victims’ families and the community.
One question remains publicly unanswered despite the fuller record: a specific motive for the two murders has not been established in the verified accounts. What is documented is the progression from two initially unexplained deaths to a homicide investigation, murder charges, evidence of two killings roughly half an hour apart, first-degree murder verdicts, rejection of an insanity defense and sentencing to permanent imprisonment.
The final judgment therefore closes a very different case from the one the public first encountered on a Saturday morning in 2023. Then, officials were correcting false reports of gunfire and could say little about how Lee and Park died. By September 2026, a jury had determined who killed them and the legal state of mind of their killer, while a judge had rejected the last request for a new sanity trial and imposed two consecutive life-without-parole terms. Li remains sentenced to spend the rest of his life in prison.
Author note: Last updated October 20, 2026.