Law enforcement sources tell us ... multiple law enforcement agencies have executed search warrants and seized computers, phones and other electronic equipment to determine who supplied Perry with the ketamine that caused him to lose consciousness last October and drown in his hot tub in Pacific Palisades, Los Angeles.

Perry had been getting ketamine infusion therapy for anxiety and depression, but the last therapy was a week and a half before his death, so the ketamine in his system was not doctor-prescribed.

TMZ broke the story, Perry had the same level of ketamine in his system that is used for general anesthesia in surgery.

Law enforcement sources tell us ... the ketamine Perry ingested was not legally prescribed and multiple agencies, including the DEA, U.S. Postal Service and LAPD, have conducted a criminal investigation for months.

We're told at least 1 doctor has been arrested, along with several dealers who helped arrange and deliver ketamine to Perry.

Our sources say the search warrant revealed text messages discussing Perry and the ketamine he wanted and what they were doing to get it to him. The texts also discuss the price the "Friends" actor would pay for the drug.

Sources tell TMZ, authorities got a search warrant for Brooke Mueller, Charlie Sheen's ex, who had been in a treatment center with Perry, but as far as we know she is not connected to the arrests. In their investigation, authorities found other celebs who were involved in the Hollywood drug scene.

TMZ broke the story of Perry's death on October 28, 2023. He was 54.

These arrests make it clear ... authorities are making it a priority to go after doctors and dealers who illegally push drugs. Notably, Ryan Reavis got an 11-year sentence as the middleman who delivered drugs laced with fentanyl to Mac Miller, resulting in the rapper's death.