Monica Moon Lee and Hee Sook Park depended on residential care when overnight caregiver Jianchun Li killed them.
DIAMOND BAR, Calif. — Monica Moon Lee and Hee Sook Park were living in a small residential home where families expected elderly residents to receive around-the-clock assistance. Instead, prosecutors said, the overnight caregiver responsible for helping protect them murdered both women within about 30 minutes.
More than three years later, that breach of trust is now at the center of a final sentence. Jianchun Li, 44, has received two consecutive terms of life in prison without the possibility of parole for the June 24, 2023, murders. A Los Angeles County jury found him guilty of two counts of first-degree murder, found a multiple-murder special circumstance true and then rejected his separate claim that he was legally insane when the killings occurred.
Park’s family had turned to the Diamond Bar home because she needed additional care. At Li’s sentencing, her son, Yun, told the court that his mother had been at the facility only about a month when she died. He described her as physically small but strong in spirit. Lee’s son, Robert, said he had also trusted the setting, telling the judge that he believed his mother was in a safe place. Their statements shifted the hearing’s focus from the mechanics of the criminal case to the reason both women were there in the first place: they relied on other people for help and supervision.
The property on Sapphire Canyon Road did not resemble a large hospital or institutional nursing complex. Contemporary reporting described Happy Home Care for Elderly as a state-licensed residential care operation inside a suburban house, with capacity for as many as six residents. Four other residents were reported unharmed when Lee and Park were found dead. The smaller setting was designed around residential living, but on the morning of the murders it became the scene of a homicide investigation that drew deputies, firefighters and paramedics into the neighborhood.
Lee, 75, used a walker. Shortly before 7 a.m., prosecutors said Li took her into a bathroom and killed her by asphyxiation with a plastic bag secured around her neck with electrical tape. Roughly half an hour later, prosecutors said, he brought Park, 83, to the same bathroom and killed her in the same manner. The description is part of the established court record, but authorities have not publicly identified a motive that accounts for why Li killed the two residents.
Emergency crews attempted lifesaving measures after arriving at the facility, but both women were pronounced dead there. Early information surrounding the case was incomplete and, at times, wrong. Some initial reports said the victims had been shot. Los Angeles County sheriff’s officials publicly rejected that account and said no shooting had occurred. Investigators initially released little about how the women died while the coroner’s work and homicide inquiry continued. The later prosecution established that both deaths resulted from strangulation or asphyxiation rather than gunfire.
The response also raised questions about the care home itself. California social services officials opened an investigation after the deaths, according to reporting at the time. Public records and news reports identified the home as a licensed residential facility serving elderly residents. The criminal prosecution, however, focused on Li’s individual actions, not a claim that other residents or employees took part in the murders. Authorities said there was no continuing threat to the surrounding community after Li was detained.
Li was arrested on the afternoon of June 24 and initially held on $4 million bail. Prosecutors filed two murder counts days later. What began as an investigation into two unexplained deaths eventually produced a detailed account of the sequence inside the home. Prosecutors said Li admitted after the killings that he had killed people, including in a 911 call. A prosecution filing also described internet searches investigators recovered from his phone involving choking, punishment for murder in California and treatment for illnesses after a first-degree murder conviction.
Those details later carried significance in a trial that involved not only whether Li committed the murders, but his mental state under California’s legal insanity standard. The jury returned its guilt verdicts Aug. 20, 2026, convicting him of both first-degree murders and finding the multiple-murder special circumstance true. Because Li had pleaded not guilty by reason of insanity, jurors then considered his sanity separately. On Aug. 27, they rejected the insanity defense.
The sentencing hearing reflected both sides of that dispute. Superior Court Judge Mike Camacho acknowledged evidence that Li was overworked, suffered from depression and had faced difficulties as a recent immigrant. The defense asked for a new trial on the sanity phase, contending that the judge’s questioning of an expert witness had weakened the defense testimony. Camacho denied that request and said there was overwhelming evidence of guilt. He also emphasized that Li had accepted responsibility for caring for both victims before knowingly violating that duty.
The judge then imposed life without the possibility of parole for each murder and ordered the terms to run consecutively. The punishment followed directly from a case in which jurors had not only convicted Li of first-degree murder but had also found the multiple-murder special circumstance. His age and the structure of the sentences mean the judgment leaves no prospect of release through ordinary parole.
The families’ statements gave the sentencing a perspective not visible in the first breaking-news reports from 2023. Robert Lee recalled the shock of receiving a call from a sheriff’s detective who would not explain what had happened until he reached the station. Yun Park described moving his mother to the home because she needed more constant attention. Those accounts underscored that the women were not simply present at the same property as their killer; they were residents of a care setting where dependence on staff was part of daily life.
District Attorney Nathan Hochman made the same point after the jury’s verdicts, saying Lee and Park were killed by the person expected to keep them safe. His office said the prosecution was handled by its Elder Abuse Section, with Deputy District Attorneys Michael Matoba and Stephanie Chavez trying the case. The Los Angeles County Sheriff’s Department conducted the criminal investigation. The specialized prosecution reflected the victims’ status as older adults in a care environment, although the convictions themselves were for first-degree murder.
There remain limits to what the public record explains. Prosecutors have detailed the sequence of the killings, Li’s admissions, evidence taken from his phone and the competing arguments about his mental condition, but no verified public account establishes a specific motive. The absence of a stated motive does not alter the verdicts or sentences, and it leaves the case’s clearest documented fact centered on the relationship that already existed: Li was working as the overnight caregiver for people who depended on the home for protection and assistance.
With Camacho’s sentencing order, the prosecution has reached its principal conclusion. Li’s request for a new sanity trial was denied, the jury’s findings remain in place and the two life-without-parole terms will run one after the other. For Lee and Park’s families, the court judgment cannot restore the safety they believed the residential home would provide, but it establishes permanent criminal punishment for the caregiver who violated that trust.
Author note: Last updated October 20, 2026.