Matthew Perry’s live-in assistant has pleaded guilty to conspiring to distribute ketamine connected to the death of the US actor.

Kenneth Iwamasa, 59, of Toluca Lake, admitted to “repeatedly injecting Perry with ketamine without medical training”, including performing multiple injections on October 28 2023 – the day he died, the Department of Justice said.

He previously pleaded guilty on August 7 “to one count of conspiracy to distribute ketamine causing death”.

Mr Iwamasa was one of five people charged after the Friends star died from an accidental ketamine overdose last October.

An investigation into the circumstances surrounding Perry’s death revealed that in autumn last year the 54-year-old actor “fell back into addiction and these defendants took advantage to profit for themselves”, United States attorney Martin Estrada said.

“Matthew Perry sought treatment for depression and anxiety and went to a local clinic where he became addicted to intravenous ketamine,” Drug Enforcement Administration (DEA) administrator Anne Milgram said.

“When clinic doctors refused to increase his dosage, he turned to unscrupulous doctors who saw Perry as a way to make quick money.”

Dr Salvador Plasencia, 42, of Santa Monica, allegedly worked with Dr Mark Chavez, 54, of San Diego, to supply Perry with large amounts of ketamine – “charging Perry 2,000 dollars (£1,500) for a vial that cost Dr Chavez approximately 12 dollars (£9)”.

“As Matthew Perry’s ketamine addiction grew, he wanted more, and he wanted it faster and cheaper, that is how he ended up buying from street dealers who sold the ketamine that ultimately led to his death,” Ms Milgram said.

Dr Plasencia allegedly used Perry’s live-in assistant Mr Iwamasa to distribute approximately 20 vials of ketamine to the actor over a two-month period from September to October 2023 “in exchange for 55,000 dollars” (£43,000).

It is claimed the doctor taught Mr Iwamasa, who had never received medical training, how to inject Perry with ketamine – including on the day he died at his Pacific Palisades home after multiple injections.

Before Perry’s death, Dr Plasencia wrote in a text message: “I wonder how much this moron will pay,” adding that Perry was “spiralling out of control with his addiction”, Mr Estrada said.

Ms Milgram said Perry “turned to street dealer” Eric Fleming, 54, of Hawthorne, who allegedly sourced ketamine from a drug trafficker known as “The ketamine Queen” – Jasveen Sangha, 41, of North Hollywood.

Mr Fleming pleaded guilty on August 8 to one count of conspiracy to distribute ketamine and one count of distribution of ketamine resulting in death, and admitted in court documents that he distributed the ketamine that killed Perry, the US attorney said.

He also is said to have admitted to obtaining the drug from Ms Sangha, and distributing 50 vials of ketamine to Mr Iwamasa – half of them four days before Perry’s death.

Ms Sangha allegedly sold approximately 50 vials of ketamine to Perry for 11,000 dollars (£8,553) in cash, the US attorney said.

“The ketamine supplied by Sangha would ultimately be the dose that took Matthew Perry’s life,” Ms Milgram told the briefing.

Perry, who most famously played Chandler Bing in hit US sitcom Friends, was found “unresponsive in the pool at his residence” in Los Angeles on October 28.

In December, Perry’s death was ruled an accident from the “acute effects of ketamine” – a sedative that can be used as a recreational drug, as well as to treat depression and pain management.

A medical examiner said that Perry had been receiving ketamine infusion therapy for depression and anxiety, with his last known treatment one-and-a-half weeks prior to his death.

“The ketamine in his system at death could not be from that infusion therapy,” the report said.

Mr Estrada said the investigation into Perry’s death uncovered a “broad underground criminal network responsible for distributing large quantities of ketamine to Perry and others”.

He said they have filed “numerous federal charges against the five defendants”, including conspiracy to distribute ketamine and distribution of ketamine resulting in death.

“With regard to defendant Plasencia, the statutory maximum sentence he faces is 120 years in federal prison. With regard to defendant Sangha, the statutory maximum she faces is life imprisonment,” Mr Estrada added.

During his life, Perry was open about his battle with substance abuse and addiction, setting up a sober living facility for men with similar issues.

Following his death, a foundation was set up in his name to help those struggling with addiction.