Jurors first convicted Jianchun Li of two murders, then separately found him legally sane when he committed them.
POMONA, Calif. — Jianchun Li’s murder trial did not end when jurors found him guilty of killing two elderly women in his care. Because he had pleaded not guilty by reason of insanity, the same jury then faced a second question: whether he was legally sane when he committed the crimes.
The answer came one week after the murder verdicts. Jurors rejected Li’s insanity defense on Aug. 27, 2026, leaving intact two first-degree murder convictions and a multiple-murder special circumstance. Superior Court Judge Mike Camacho later sentenced Li, 44, to two consecutive terms of life in prison without the possibility of parole for the June 24, 2023, killings of Monica Moon Lee, 75, and Hee Sook Park, 83, at a Diamond Bar residential care facility.
The sanity phase placed Li’s mental condition directly before the jury without reopening the basic question of who killed the women. Prosecutors had already persuaded jurors that Li committed both murders and did so with the state of mind required for first-degree murder. The separate proceeding concerned the legal effect of his mental condition at the time. Evidence cited at sentencing showed Li had suffered from depression, had been overworked and had faced difficulties as a recent immigrant. Jurors nevertheless found that he was legally sane.
That finding survived a final defense challenge at sentencing. Defense attorney Ivonne De La Cruz asked Camacho for a new trial on the sanity phase, arguing that the judge’s questioning while a defense expert testified had substantially undermined the witness. Camacho denied the motion. According to an account of the hearing, he said the jury would have reached the same decision even without his intervention. He then moved to sentencing, where the murder verdicts and special-circumstance finding exposed Li to life imprisonment without parole.
Camacho said the evidence of guilt was overwhelming and focused in part on Li’s role before the murders. Li had taken on responsibility as an overnight caregiver at Happy Homes Care, a residential facility for elderly women on Sapphire Canyon Road. The judge noted that Li had a duty of care toward both victims and had knowingly accepted that responsibility. That duty became especially important because the evidence showed the killings were carried out against residents who relied on the home and its staff.
The underlying sequence unfolded in less than an hour. Prosecutors said Li brought Lee, who used a walker, into a bathroom shortly before 7 a.m. and killed her by asphyxiation with a plastic bag secured around her neck with electrical tape. About 30 minutes later, he brought Park into the same bathroom and killed her in the same manner. Emergency personnel later attempted to save the women, but both were pronounced dead at the facility.
Evidence about Li’s actions after the deaths also became part of the prosecution’s case. A prosecution trial filing cited during coverage of the sentencing said Li called 911 and acknowledged killing people. The filing also said he made another admission after a nurse arrived. Investigators who examined his phone found internet searches about choking, the potential sentence for murder in California and whether people convicted of first-degree murder could receive treatment for illnesses, according to the filing.
Those facts were among the circumstances available to prosecutors as they argued that Li understood what he was doing. The jury’s sanity verdict did not require jurors to conclude that he had no mental illness or personal difficulties. The evidence discussed at sentencing showed that mental-health issues were part of the case. But the legal question before the jury was narrower than whether Li had ever experienced depression or other problems, and jurors rejected the defense that would have treated him as legally insane at the time of the murders.
Li’s prosecution had begun under far less certain circumstances in June 2023. Deputies were sent to the Diamond Bar care home after two residents were found unresponsive. Early reports provided little information about how they died, and some initial accounts incorrectly described the case as a shooting. Sheriff’s officials said the women had not been shot. Paramedics tried to provide aid, and homicide detectives took over the investigation after both residents were declared dead.
Li, then 40, was arrested that afternoon and initially held in lieu of $4 million bail. Prosecutors filed two murder charges days later. Contemporary reporting described the location as a state-licensed residential care home with space for up to six residents, while authorities said four other residents were unharmed. California social services officials also opened a review of the facility. The criminal case against Li, however, focused on the deaths of Lee and Park and gradually developed the detailed evidence later presented to jurors.
By August 2026, prosecutors were prepared to try the case through both its guilt and sanity phases. The Los Angeles County District Attorney’s Office said the jury convicted Li of two counts of first-degree murder on Aug. 20 and found the special circumstance of multiple murders true. One week later came the legal sanity verdict. That sequence mattered because a guilty verdict alone did not resolve the defense Li had raised; the second verdict was necessary before the case could proceed toward the punishment eventually imposed.
The sentencing hearing also allowed relatives to speak about consequences that did not fit neatly within the legal questions posed to jurors. Lee’s son, Robert, told the court about receiving a call from a sheriff’s detective and learning that the place he considered safe for his mother had become the scene of her death. Park’s son, Yun, said his mother had moved to the facility because she needed increased care and had lived there for only about a month before she was killed.
Los Angeles County District Attorney Nathan Hochman said after the trial that the victims had been killed by the person expected to keep them safe. His office credited Deputy District Attorneys Michael Matoba and Stephanie Chavez with prosecuting the case through the Elder Abuse Section of the White Collar Crime Division. The Los Angeles County Sheriff’s Department investigated. Prosecutors have publicly laid out the timing, method, admissions and other evidence surrounding the murders, but a specific motive has not been established in the verified public accounts.
Camacho’s sentence followed the jury’s findings rather than resolving a new factual dispute. The court denied the defense request to redo the sanity phase, accepted the verdicts already returned and imposed life without parole for each murder, with the terms to run consecutively. The result leaves Li with no ordinary prospect of parole and preserves the jury’s two-part conclusion: he committed first-degree murder twice, and he was legally sane when he did so.
The case is therefore notable not only for the punishment but for the route taken to reach it. Three years after two elderly residents died inside a Diamond Bar care home, a jury separately addressed criminal guilt and legal sanity, a judge upheld both determinations over a defense challenge, and Li received consecutive life-without-parole sentences. Those rulings now define the legal outcome of the murders of Lee and Park.
Author note: Last updated October 20, 2026.