Presley Gerber's Doctor Was Giving Him Ketamine, Sources Say

Presley Gerber's doctor was prescribing him ketamine despite his known issues with the substance ... TMZ has learned.

People who were in regular contact with Presley and who have direct knowledge tell TMZ ... a doctor was giving him ketamine despite knowing about his drug addiction issues. Ketamine can be used to treat drug addiction, though that's not its FDA-approved intention.

Ketamine was a regular problem for Presley, we're told ... and close friends are angry the doctor prescribed the substance to him -- and they think the doc should be prosecuted.

To be clear ... we still don't know what drugs might have been in Presley's system when he died -- just that Presley opened up about his issues with ketamine to close friends before he passed away.

Presley's situation sounds eerily similar to Matthew Perry's before his 2023 death. Remember, Matthew -- who dealt with drug addiction for years -- was prescribed ketamine for depression and anxiety.

Mathew, however, began to get ketamine from other sources ... specifically the "Ketamine Queen" Jasveen Sangha, who was sentenced to 15 years in prison for her role in Perry's death.

We broke the story ... Presley died in a rehab facility on Sunday. He is believed to have died from an overdose, but the official cause of death is still pending.

Sources who had contact with Presley in his final few hours told us he looked like he was under the influence at the rehab center. The source of the alleged drugs is still being investigated ... and police have even interviewed other rehab patients.

In the months before his death, Presley was trying alternative treatments for addiction ... including ibogaine -- a psychoactive substance which some believe opens up new neural pathways and can help people addicted to drugs.