The pills are commonly used to treat pain, and investigators have brought in the U.S. Drug Enforcement Administration to help with the case, the source said.
Investigators believe a health scare about a week before Prince’s death, which caused an unscheduled landing of his plane in Illinois, was likely the result of a reaction to the pain medication, the official said.
The pilot told air traffic control a passenger, later known to be Prince, was unresponsive.
Prince was treated for a potential overdose of pain medication, the official said.
— CNN (@CNN) April 28, 2016
Investigators are still awaiting results of autopsy and toxicology tests for further understanding of why Prince died.
Prince was 57 when he died last week at his home in a Minneapolis suburb.