'Monster who killed him': Matthew Perry's former assistant gets more than three years in prison

LOS ANGELES - A former live-in assistant to Matthew Perry was sentenced Wednesday to more than three years in prison after repeatedly injecting the actor with ketamine, including the fatal dose that killed him.

Kenneth Iwamasa, who previously made $150,000 a year working for Perry, pleaded guilty in August 2024 to conspiracy to distribute ketamine causing death. He admitted to repeatedly injecting Perry, 54, with ketamine without medical training, including multiple injections on Oct. 28, 2023 - the day of Perry's death.

Perry, who had a history of drug abuse and addiction, was found dead in the hot tub of his Pacific Palisades home from acute effects of the drug. Iwamasa was among five people charged in connection with Perry's death and is the final one to be sentenced.

The judge ordered Iwamasa, 61, to self-surrender by July 17 and to pay a $10,000 fine.

"You were privy to his struggle with addiction," U.S. District Judge Sherilyn Peace Garnett told Iwamasa, as she handed down the sentence. "Your conduct was reckless, not just on the day of his death but leading up to his death."

Prosecutors had asked for the 41-month sentence that Garnett handed down; Iwamasa's defense attorneys had asked for six months of incarceration and six months of home confinement.

While prosecutors noted in their sentencing memo that Iwamasa was the first defendant to cooperate against the others, they cited the former assistant's responsibility for Perry's medical care, knowledge of the actor's addiction struggles and steps to remove and destroy evidence after Perry's death.

During the hours-long sentencing hearing, Assistant U.S. Atty. Ian Yanniello said Iwamasa obtained more than 70 vials of ketamine for the actor in a month.

"This case is about a breach of trust. ... Mr. Perry wanted to overcome his demons and live a sober life," Yanniello said. "(Iwamasa) became Mr. Perry's drug supplier and enabler."

Iwamasa's attorney, Alan Eisner, stressed that "Mr. Perry was not a bystander here" and said the actor was "not blameless in the events that led to his own death." He added that Iwamasa "didn't have the spine to say no to his boss."

"He was unable to say no."

"Unwilling - not unable," Garnett replied.

"You're right, he could have said no and shame on him for not saying no," Eisner said. "He didn't have the strength of character to do that."

While addressing the court, Lisa Ferguson, Perry's longtime business manager and the appointed executor of his estate, scoffed at the idea that Iwamasa had no power in the situation. She accused Iwamasa of wanting "control over Matthew and everything he owns."

Perry, Ferguson said, "was terrified of dying. He wanted to live."

"What you are," she told Iwamasa, "is the monster who killed him."

"Matthew deserved to live," Ferguson added. "You don't."

Iwamasa, whose father and brother attended the hearing, turned to Perry's family and loved ones in the front row and offered them an apology.

"I'm sorry to have done illegal acts that I will forever regret. I'll take that to my grave," Iwamasa said, later clasping his hands as if in prayer. "I'm horribly, horribly sorry. And I offer my condolences to you."

After the sentencing hearing, Eisner and Dmitry Gorin, Iwamasa's attorneys, said their client "cared tremendously for Mr. Perry and continues to feel deep remorse over what happened."

"He worked in the industry for decades, had never been in trouble with the law, and was respected by friends and family," they said. "Although we are all disappointed in the sentence, Mr. Iwamasa has grown from this tragedy and looks forward to pursuing new goals and achieving positive accomplishments in his life."

In letters to the judge ahead of sentencing, Perry's loved ones said the actor had considered Iwamasa "family." Suzanne Morrison, Perry's mother, said Iwamasa's No. 1 responsibility "was to be my son's companion and guardian in his fight against addiction."

After Perry's death, Morrison wrote, Iwamasa insisted on speaking at the funeral and clung to the family, "as if he was somehow the good guy who tried to save Matthew." She accused Iwamasa of threatening legal action "to pry a settlement from workman's comp."

"We trusted a man without a conscience, and my son paid the price," Morrison wrote.

Iwamasa had known Perry since around 1992 and became his live-in assistant in 2022, according to prosecutors. His responsibilities included coordinating medical appointments and helping ensure Perry took medication that he was lawfully prescribed.

Ferguson, who served as Perry's business manager since he was 22, said she had to talk the actor into hiring Iwamasa, calling it a "grave mistake." She accused Iwamasa of convincing Perry to fire his sober companions in the months leading up to his death.

"Your plan was to be in control," she said.

According to Iwamasa's plea agreement, around September 2023, Perry requested Iwamasa's help procuring illegal drugs.

Throughout October 2023, prosecutors said, Iwamasa repeatedly injected Perry "with doses of ketamine without proper medical training or the equipment necessary to ensure the drug was being safely administered." They cited the fact that Iwamasa saw "clear warning signs that Mr. Perry was in danger."

At least twice in October, Iwamasa found Perry unconscious in his home and also saw Perry "freeze up," unable to speak after a large ketamine injection, according to the government's sentencing memo. Despite that, prosecutors said, between Oct. 24 and Oct. 27, Iwamasa injected Perry with six to eight shots per day.

Iwamasa admitted that on the day of Perry's death, at the actor's direction, he injected Perry with a shot of ketamine in the morning and again while he watched a movie around midday. Less than an hour later, Perry asked Iwamasa to prepare the hot tub and "shoot me up with a big one."

According to the plea agreement, Iwamasa filled a syringe with ketamine and administered it to Perry while the actor was in or near the tub. Soon after, Iwamasa left to run errands for Perry. When he returned, he found Perry's body.

While being questioned by police officers, prosecutors said, Iwamasa concealed the injections he'd administered and "also took steps to remove and destroy evidence related to Mr. Perry's use of ketamine in the days leading up to his death."

Prosecutors said Iwamasa later provided "significant and credible information related to the drug conspiracy."

This month, a judge sentenced Erik Fleming, a former producer and drug counselor, to two years in prison for distributing the ketamine that killed Perry. Jasveen Sangha, known as the "Ketamine Queen," was sentenced last month to 15 years in prison.

Salvador Plasencia, a former physician who supplied ketamine to Perry in the weeks leading up to his death, previously was sentenced to 30 months in prison. Mark Chavez, another former doctor who played a role in providing the actor ketamine, was sentenced to eight months of house arrest.

In Morrison's letter to the judge, she thanked the investigators for discovering the truth about Iwamasa and the judge for her "calm and careful deliberation."

"And I have to say this: the word 'closure.' Such a thing doesn't exist," she wrote. "Ask any mother whose child has been torn away so mercilessly. Nothing takes this pain away, nor will it, I am sure, for as long as I live."

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This story was originally published May 27, 2026 at 10:50 AM.