Authorities have arrested at least one person in connection with Matthew Perry's death, a law enforcement official tells The Associated Press.

The official was not authorized to discuss details of the ongoing investigation and spoke to AP on condition of anonymity. Authorities have scheduled a news conference in Los Angeles to announce details in the case later Thursday morning.

Los Angeles police said in May that they were working with the U.S. Drug Enforcement Administration and the U.S. Postal Inspection Service with a probe into why the 54-year-old had so much of the surgical anesthetic in his system.

An assistant found Perry face down in his hot tub on Oct. 28, and paramedics who were called immediately declared him dead.

His autopsy, released in December, found that the amount of ketamine in his blood was in the range used for general anesthesia during surgery.

The decades-old drug has seen a huge surge in use in recent years as a treatment for depression, anxiety and pain. People close to Perry told coroner’s investigators that he was undergoing ketamine infusion therapy.

But the medical examiner said Perry’s last treatment 1 1/2 weeks earlier wouldn’t explain the levels of ketamine in his blood. The drug is typically metabolized in a matter of hours. At least two doctors were treating Perry, a psychiatrist and an anesthesiologist who served as his primary care physician, the medical examiner’s report said. No illicit drugs or paraphernalia were found at his house.

Ketamine was listed as the primary cause of death, which was ruled an accident with no foul play suspected, the report said. Drowning and other medical issues were contributing factors, the coroner said.

Perry had years of struggles with addiction dating back to his time on “Friends,” when he became one of the biggest television stars of his generation as Chandler Bing alongside Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc and David Schwimmer for 10 seasons from 1994 to 2004 on NBC’s megahit sitcom.