Biggest revelations in the investigation into the death of Matthew Perry

California authorities provide further details on arrests in connection with the death of Friends Star Matthew Perry – including claims that some of those arrested were aware that they were using Perry for financial gain.

On August 15, U.S. Attorney Martin Estrada announced that several people had been charged in connection with Perry's death, including two doctors and his personal assistant who lived with him.

“Each of the defendants played a key role in his death,” said Anne Milgram of the U.S. Drug Enforcement Administration at the live-streamed press conference on August 15.

The former Friends Star died of an accidental drug overdose on Oct. 28 at age 54. Perry died from the acute effects of ketamine, according to an autopsy report obtained by PEOPLE. Other contributing factors included drowning, coronary artery disease and the effects of buprenorphine, a medication used to treat opioid use disorder.

What you should know:

Who are the defendants?

The five arrested include Perry's personal assistant, two doctors and a suspected drug dealer who, according to Estrada, “exploited Perry for his own profit.”

Authorities named Jasveen Sangha, allegedly known as the “Ketamine Queen,” and Dr. Salvador Plascencia as the first two defendants in the case.

Perry's assistant Kenneth Iwamasa was also charged – and has already pleaded guilty – alongside Erik Fleming and Dr. Mark Chavez, the Justice Department announced.

“These defendants exploited Mr. Perry's addiction issues to enrich themselves,” Estrada said at the press conference. “Ultimately, these defendants were more interested in profiting from Mr. Perry than in caring about his well-being.”

What fees apply?

The charges – and the defendants' subsequent pleas – vary for each defendant, with Sangha facing multiple charges related to drug possession and trafficking.

She is charged with one count of conspiracy to distribute ketamine, one count of operating drug premises, one count of possession of methamphetamine with intent to distribute, one count of possession of ketamine with intent to distribute and five counts of distribution of ketamine, the Justice Department said.

Plascencia is charged with conspiracy to distribute ketamine. Sangha and Plascencia will both be tried at a later date.

According to the Justice Department, Iwamasa pleaded guilty to one count of conspiracy to distribute ketamine resulting in death.

Fleming pleaded guilty to one count of conspiracy to distribute ketamine and one count of distribution of ketamine resulting in death. Chavez will plead guilty to one count of conspiracy to distribute ketamine, according to the Justice Department.

The defendants tried to “cover up” evidence, officials say

The defendants were allegedly aware of the negative impact their actions would have on Perry's health and well-being, but continued to supply him with the drugs anyway, authorities said at the press conference.

Among other things, the authorities said they found text messages in which Sangha wrote: “I wouldn't do it if I didn't have the chance to make money from it,” Estrada said at the press conference.

He further claimed that the text exchanges showed that the defendants were allegedly aware that the way they administered the ketamine was not the correct one.

After Perry's death, the defendants attempted to “cover up” their involvement, Estrada claimed, adding that Sangha allegedly wrote in a text message to another defendant: “Delete all our messages.”

The investigation

Thursday's announcement follows a months-long investigation involving the U.S. Attorney's Office, the Los Angeles Police Department, the Drug Enforcement Administration and the Los Angeles Division of the U.S. Postal Inspection Service.

The LAPD began investigating the star's death in May after the Los Angeles County Coroner's Office completed its investigation.

In December, the Los Angeles County Medical Examiner's Office completed its investigation into his death, PEOPLE reported at the time. The cause of death was ruled an accident.

After the medical examiner released his report on Perry's death, the LAPD launched an investigation into the circumstances of his overdose death in December, the department confirmed to PEOPLE in May.

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Perry was best known for his role as Chandler Bing in the 90s sitcom. Friends. Throughout his career, he spoke highly of the role that gave him – and fellow actors Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc and David Schwimmer – their breakthrough into fame.

If you or someone you know is struggling with substance abuse, please call the SAMHSA Helpline at 1-800-662-HELP.