Federal authorities said their investigation into Perry’s death uncovered a “broad underground criminal network" of drug suppliers who distributed large quantities of ketamine across Los Angeles.

Federal court documents detail Perry’s last months alive and the transition from his treatments at a ketamine clinic for depression and anxiety, where a physician administered the drug and monitored for side effects, to an addiction that led him to “unscrupulous doctors” and a network of street dealers.

Perry had been open about his addiction problems, which stem back decades - even to his time playing Chandler Bing on “Friends”. If a drug entered his life, he seemed to become addicted.

But in his memoir Friends, Lovers, and the Big Terrible Thing, he said he’d finally got sober, and one woman told investigators at the coroner’s office that she believed he’d been sober for 19 months.

Somewhere in that time, he started receiving ketamine infusion therapy. Experts say Perry’s history of addiction helped lead him to quickly become hooked on the drug.

The federal investigation found that over a nearly two-month span before his death, Perry purchased dozens of vials of ketamine for thousands of dollars.

Over the three days before his death, his assistant injected him at least six times a day with ketamine shots.

Five people were arrested in the probe - three of whom already pleaded guilty in the conspiracy. In total, the group faces 23 counts in Perry's death.

• Kenneth Iwamasa: Perry's live-in personal assistant pleaded guilty to one count of conspiracy to distribute ketamine causing death. He admitted to helping Perry find ketamine and repeatedly injecting him with the drug, including the dose that killed him.
• Dr Salvador Plasencia: A physician accused of supplying Perry with large quantities of ketamine, injecting him on multiple occasions - including in a public parking lot - and teaching his assistant how to inject him with doses. He has pleaded not guilty to all charges against him arising out of Perry's death.
• Dr Mark Chavez: A physician who pleaded guilty to one count of conspiracy to distribute ketamine. He admitted to selling ketamine to Dr Plasencia, including drugs he had diverted from a ketamine clinic.
• Jasveen Sangha, described by law enforcement as the “The Ketamine Queen": An alleged street dealer who court documents say was known to work with celebrities and high-end clients. She is accused of supplying the drugs that ultimately killed Perry. Authorities raided her home and discovered what they called a "drug-selling emporium" with dozens of ketamine vials and thousands of pills. She has pleaded not guilty to all charges against her, including conspiracy to distribute ketamine and distribution of ketamine resulting in death.
• Eric Fleming: A middleman who authorities say got drugs from Ms Sangha and distributed them to Perry and his assistant. He pleaded guilty to one count of conspiracy to distribute ketamine and one count of distribution of ketamine resulting in death.