The painkiller Percocet was present in Prince's body when he was found dead April 21 in a Paisley Park elevator, a source familiar with the investigation said Wednesday.
However, it is not yet clear whether the potent opioid caused or contributed to the musician's death, the source stressed.
The revelation came on the same day that federal law enforcement authorities joined the investigation into the death of Prince, who was seeking emergency help for an addiction to opioid painkillers during the week of his collapse.
The Drug Enforcement Agency (DEA) and the U.S. attorney's office announced that they were assisting Carver County investigators following the public disclosure that a California physician had been called for addiction treatment. The doctor was scheduled to meet Prince in the Twin Cities the day after the artist was found dead.
Criminal investigators are scrutinizing how Prince acquired the painkillers, or any medications used to treat the addiction.
A spokesman for the U.S. attorney's office declined to comment Wednesday, other than to say that federal officials can advise Carver County investigators regarding the diversion of prescription drugs beyond their prescribed uses. Confronting the diversion of opioid pain medications has been a priority for the DEA, the Department of Justice and U.S. Attorney Andrew Luger.
"While this remains an ongoing investigation, we will have no further comment," the spokesman said Wednesday.
Prince was pronounced dead at 10:07 a.m. April 21, 19 minutes after emergency responders arrived after receiving a 911 call. The cause of death remains undetermined, pending the results of an autopsy and toxicology tests. While those tests have not been completed, they showed that Percocet was present, the source said Wednesday night.