STORY: Los Angeles police said Tuesday that detectives and federal agents are investigating the death of "Friends" star Matthey Perry.

They are looking into how he obtained the high dose of the powerful prescription drug ketamine that was found in his body and determined to have caused his death.

The disclosure of the probe by the police, the Drug Enforcement Agency and the US Postal Inspection Service comes five months after the actor's death.

The Los Angeles County medical examiner concluded Perry succumbed to an accidental drug overdose and drowning, with no foul play suspected.

The autopsy said toxicology tests found ketamine, a short-acting anesthetic with hallucinogenic properties, in Perry's body at dangerously high levels well within the range typically associated with general anesthesia used in monitored surgical care.

Coronary artery disease, the effects of the opioid-addiction medicine also detected in his system, and drowning were listed as contributing factors in his Oct. 28 death.

Witness interviews in the report said he had been undergoing ketamine infusion therapy for depression and anxiety.

But the autopsy said his last known treatment was a week and a half before his death, so the ketamine found in his system by medical examiners would have been introduced since that last infusion.

A police spokesperson said the focus of the investigation is how Perry might have obtained ketamine on his own or who might have given it to him.