Matthew Perry's former assistant sentenced to 41 months in ketamine death case

Kenneth Iwamasa, Matthew Perry’s former live-in personal assistant, was sentenced on Wednesday to 41 months in federal prison and ordered to pay a $10,000 fine, sealing the last open chapter in the drug-conspiracy case tied to the actor’s death.

Iwamasa, 61, of Toluca Lake, pleaded guilty in August 2024 to conspiracy to distribute ketamine resulting in death and serious bodily injury. Prosecutors said he repeatedly injected Perry with ketamine, including the fatal dose that ended the Friends star’s life in October 2023. By the time the sentence was imposed, federal authorities had already treated the case not as a one-off overdose, but as a broader criminal scheme built around Perry’s inner circle.

That theory ran through the entire prosecution. Iwamasa, who had known Perry since 1992 and began working as his live-in assistant in 2022, was described as helping coordinate medical care and medication before becoming part of the distribution chain. Prosecutors said he worked with physician Salvador Plasencia and drug counselor Erik Fleming to supply ketamine to Perry in the months before the actor died.

The government’s case painted Plasencia as a key source. Prosecutors said he distributed ketamine vials, tablets and syringes, and taught Iwamasa how to inject Perry, even though the conduct fell below the proper standard of medical care and lacked a legitimate medical purpose. Court filings also said Plasencia charged $57,000 for the effort, while the actual going price of ketamine was far lower. In that version of events, Perry was not simply a patient in trouble but the center of a drug pipeline that relied on access, trust and repeated betrayals.

Iwamasa is now the fifth and final defendant sentenced in the case, and his punishment closes out the federal conspiracy that grew from a death investigation into a multi-defendant prosecution. For prosecutors, the endgame was always about accountability: who supplied the ketamine, who taught the injections, and who kept the chain moving until the dose that killed Perry. With Iwamasa’s sentence, that chain now ends in federal prison.