The text was written by Salvador Plasencia, a medical doctor known as "Dr. P", who is one of five defendants charged in relation to the actor's death, according to prosecutors.

Others charged include Jasveen Sangha, known as the "Ketamine Queen", Kenneth Iwamasa, Perry's live-in personal assistant, Erik Fleming, an acquaintance of the TV star, and another doctor, Mark Chavez.

Iwamasa and Fleming have already pleaded guilty to charges relating to Perry's death, while Chavez, a San Diego physician, has agreed to plead guilty to conspiracy to distribute ketamine.

On Thursday afternoon, Plasencia pleaded not guilty to the charge against him, and his trial is scheduled to start on 8 October.

The judge agreed to a $100,000 (£77,796) bail bond with some additional conditions.

Plasencia was also granted permission to keep running his medical practice "not related to controlled substances" while on bail as long as he posted a notice explaining his circumstances and that each patient signed a form stating they knew about the charges against him.

Sangha pleaded not guilty but was not released on bail, as she had already been on bail after being arrested in March for a previous drug charge.

That bail bond was rescinded on Thursday due to the concern of flight risk and the fact that she had asked a co-conspirator to delete text messages.

Her trial is scheduled for 15 October.

It comes after Perry was found dead in a swimming pool at his California home in October 2023.

A grand jury indictment, filed in California, alleges Plasencia sold ketamine and paraphernalia such as syringes to Perry's assistant - and taught him how to inject the drug - after the actor developed an addiction while seeking mental health treatment.

Ketamine has in recent years seen a huge surge in use, as a treatment for depression, anxiety and pain.

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

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

Prosecutors allege Chavez funnelled ketamine to Plasencia, securing some of the drug from a wholesale distributor through a fraudulent prescription.

In one instance, prosecutors allege that Plasencia "charged Perry $2,000 (£1,500) a vial that cost Dr Chavez approximately $12 (£9)".

Across a two-week period in early October 2023, Plasencia received $32,000 from Iwamasa - including $21,500 in cash - in exchange for ketamine, the indictment alleges.

"These defendants took advantage of Mr. Perry's addiction issues to enrich themselves. They knew what they were doing was wrong," US Attorney Martin Estrada said.

Prosecutors say Perry suffered a health scare on 12 October, when he "froze up" and suffered high blood pressure after being injected with a "large dose" of the tranquilliser.

"Let's not do that again," Plasencia wrote to Iwamasa after the incident.

But in the days leading up to Perry's death, his assistant was administering "at least six shots" of ketamine to the actor a day.

In mid-October, Iwamasa also allegedly began obtaining ketamine from Perry's acquaintance Fleming and "Ketamine Queen" Sangha.

Assistant administered ketamine to Friends star

Iwamasa injected "at least three shots" of ketamine to the Friends star on 28 October 2023, "resulting in [his] death and serious bodily injury". Iwamasa is the one who found Perry dead in his California home.

The prosecutor said the defendants exchanged messages referencing ketamine as the cause of Perry's death soon after it happened.

At a press conference announcing the charges, Mr Estrada said they also tried to cover up their involvement in supplying the actor with the drug.

The Los Angeles County Medical Examiner's Office attributed Perry's death to the acute effects of ketamine - a sedative that can be used as a recreational drug, as well as to treat depression.

Police said back in May that they were working with federal authorities to investigate the source of the ketamine the 54-year-old actor had consumed.

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Perry had been undergoing ketamine infusion therapy to treat depression and anxiety, but his last session took place more than a week prior to his death, a post-mortem report found in December.

The report said the amount of ketamine in his blood was in the range used for general anaesthetic during surgery.

The star had been open about his battle with substance abuse and addiction and also set up a sober living facility for men with similar issues.