One of two California doctors in the drug-related death of actor Matthew Perry has pleaded guilty in the case.

On Wednesday, Dr. Mark Chavez, who is among the five people charged in the overdose death of the "Friends" star, pleaded to illegally distributing the drug ketamine.

It is a short-acting anaesthetic that is also used as a treatment for depression and in pain management.

Perry died at age 54 in October 2023, and according to an autopsy report, he passed away from the "acute effects" of ketamine and other factors that caused him to lose consciousness and drown in his hot tub.

Chavez entered the plea during an appearance in the U.S. District Court in Los Angeles and could face up to 10 years in prison at his sentencing, which is scheduled for April.

He pleaded guilty under an agreement with prosecutors, who offered him lesser charges for his assistance in their case against another physician charged in the case, Dr Salvador Plasencia as well as co-defendant Jasveen Sangha, who authorities believe was an illicit supplier of the drug and was known as the "ketamine queen”.

Dr. Mark Chavez, who is among the five people charged in the overdose death of the "Friends" star. Picture: X.

"He has accepted responsibility. He is cooperating," Reuters reported Perry's attorney, Matt Binninger, as saying in court.

The 54-year-old is believed to have operated a ketamine clinic and has been accused of selling ketamine lozenges to Plasencia, who supplied them to Perry.

Chavez has also since relinquished his medical licence and remains free on bail until his sentencing.

Meanwhile, Plasencia and Sangha have pleaded not guilty and their trials are scheduled to start in March.

In addition, Perry's live-in personal assistant, Kenneth Iwamasa, who admitted to injecting the actor with the drug, as well as an alleged middleman who said he obtained ketamine from Sangha, have also already pleaded guilty to charges they faced.

Reuters reported that authorities believe that Plasencia bought the drug from Chavez.

They added that Iwamasa wrote in a text message to the doctor in regards to the amount for the drug: "I wonder how much this moron will pay."

Iwamasa has also since admitted to providing ketamine to Plasencia, even though he understood it should only be administered under medical supervision with proper safety equipment nearby.

According to court documents, Plasencia administered the ketamine to Perry at his home. He also supplied the vials that were injected by Iwamasa.

But the doctor’s lawyer has insisted that his client properly prescribed and administered ketamine to Perry.

Perry has a history of substance abuse which includes using ketamine while he played Chandler Bing on the hit show, opposite Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc and David Schwimmer.