A Los Angeles County jury found Jianchun Li guilty of murdering two elderly women at an assisted living facility in Diamond Bar in June 2023, bringing a three-year-old case to a major legal conclusion.
Li was working as an overnight caretaker at Happy Homes Care, a residential care facility for elderly women at 23801 Sapphire Canyon Road, when prosecutors say he killed Monica Moon Lee, 75, and Hee Sook Park, 83.
The killings occurred during the early morning hours of June 24, 2023.
According to the Los Angeles County District Attorney's Office, Lee used a walker and was being assisted by Li shortly before 7 a.m. Li allegedly escorted her to a bathroom before placing a plastic bag over her head, wrapping electrical tape around her neck and strangling her.
Approximately 30 minutes later, prosecutors said Li took Park to the same bathroom and killed her in the same manner.
Firefighters responded to the facility and attempted lifesaving measures on both women. Despite those efforts, both victims were pronounced dead at the scene.
The circumstances of the killings were especially significant because Li was employed as a caretaker, a role that placed him in a position of responsibility toward elderly residents who depended on staff members for assistance and safety.
Los Angeles County District Attorney Nathan J. Hochman described the victims as vulnerable women who had been entrusted to Li's care.
“Three years ago, Monica Moon Lee and Hee Sook Park’s lives were brutally taken by Jianchun Li, the very person expected to keep them safe,” Hochman said.
WHAT THE JURY DECIDED
The jury reached its initial verdict on Aug. 20, 2026, finding Li guilty of two counts of first-degree murder.
Jurors also found true the special circumstance allegation involving multiple murders. That finding significantly affects the potential sentence Li faces.
The case did not end with the murder convictions, however. The court proceeded to a separate sanity phase because Li had raised a not-guilty-by-reason-of-insanity defense.
On Aug. 27, the jury delivered its verdict in that phase and rejected the defense, determining that Li was legally sane when he committed the murders.
The decision means the jury did not accept the argument that Li's mental state legally excused him from responsibility for the killings.
District Attorney Hochman thanked jurors for both holding Li responsible for the murders and rejecting the insanity defense.
“I thank the jury for holding Li responsible and finding him sane when he made the decision to kill two vulnerable women who were entrusted to his care,” Hochman said.
The prosecution was handled by the Elder Abuse Section of the White Collar Crime Division. Deputy District Attorneys Michael Matoba and Stephanie Chavez prosecuted the case.
Hochman praised the prosecutors for their work on behalf of the victims and their families.
“Li’s conviction is a testament to the tremendous work the prosecutors in our Elder Abuse Section do every day to fight for elders and dependent adults, who are among our community’s most vulnerable victims,” Hochman said.
THE INSANITY DEFENSE
The rejection of Li's insanity defense represents an important part of the jury's final determination.
A not-guilty-by-reason-of-insanity defense does not simply dispute whether a defendant committed an act. It raises a separate legal question concerning the defendant's mental state and whether that state meets the applicable legal standard for insanity.
In Li's case, jurors rejected that defense during the sanity phase on Aug. 27, following their earlier determination that he was guilty of the two murders.
That verdict does not mean the defense's position was never considered. Rather, the jury heard the relevant evidence and ultimately determined that Li did not meet the legal standard necessary for a not-guilty-by-reason-of-insanity finding.
The distinction is important because the murder convictions and the sanity determination were separate phases of the proceedings.
With both phases now decided against Li, the case is moving toward sentencing.
WHAT HAPPENS NEXT
Li faces life in prison without the possibility of parole based on the convictions and special circumstance finding.
His sentencing is scheduled for Sept. 3, 2026, in Department P of the Pomona Courthouse South.
The sentencing hearing will formally determine the punishment following the jury's verdicts.
For the families of Lee and Park, the sentencing will mark another significant stage in a case that began with their deaths more than three years ago.
Hochman said prosecutors hoped the verdict would provide some measure of closure to those affected by the killings.
“We hope this verdict brings a measure of closure to the victims’ loved ones and the Diamond Bar community,” Hochman said.
He added, “Justice was served and Li will be held fully accountable for his horrific and senseless crimes.”
The case, identified as KA133243, was prosecuted by the Elder Abuse Section of the White Collar Crime Division and investigated by the Los Angeles County Sheriff's Department.
THE BIGGER QUESTION
The convictions also highlight the particular vulnerability of elderly residents living in residential care facilities.
People living in these settings may rely on caretakers for basic daily needs, mobility assistance and protection. That dependence can make allegations of abuse or neglect especially serious when the alleged offender is someone entrusted with providing care.
In this case, prosecutors alleged that both women were taken to the same bathroom and killed within roughly half an hour of one another. The jury's first-degree murder verdicts and multiple-murder special circumstance finding established Li's criminal responsibility under the jury's determination.
At the same time, the rejected insanity defense demonstrates why criminal trials can involve multiple legal questions. The jury was required to determine not only whether Li was guilty of the murders but also whether his mental state satisfied the legal requirements for an insanity verdict. Jurors ultimately rejected that defense.
The case serves as a reminder that families and caregivers play an important role in recognizing potential signs of elder abuse, neglect or mistreatment.
The Los Angeles County District Attorney's Office encourages anyone who suspects physical abuse, emotional abuse or neglect of an elderly person to contact local law enforcement or the Los Angeles County Elder Abuse Hotline at 1-877-4R SENIORS (1-877-477-3646).
The DA's Office also provides educational materials explaining how members of the public can identify and report suspected elder abuse.
For Lee and Park's families, however, the criminal case has centered on two women whose lives ended while they were living in a place where they were supposed to receive care and protection.
The upcoming sentencing will now determine the final punishment for Li following the jury's findings.