The Minneapolis Star Tribune quotes a source close to the investigation as saying that the prescription opiate painkiller was detected in the music legend's body – however the source cautioned that investigators do not yet know whether it played a role in his April 21 death.
Although an autopsy for the singer has been completed, a cause of death for the 57-year-old has not been revealed.
The news comes one day after a prominent addiction specialist Dr. Howard Kornfeld revealed that he was contacted by Prince's representatives about treating him for a drug addiction.
Sources previously told PEOPLE that Prince once had a history of using the prescription painkiller.
Liu Heung Shing / AP
Although the star is known for clean-living and abstaining from recreational drugs, sources said he may have used the opiate to treat pain he suffered due to years of high-energy onstage performances.
"His hip bothered him from jumping off risers for 20 years," Sheila E., who collaborated and once dated the star, told PEOPLE.
In the days following his death, speculations about Prince's supposed drug use arose and it was revealed that the "Purple Rain" singer was expected to meet with a doctor to discuss treatment for the supposed prescription painkiller addiction just one day before his death.
Less than a week after his death, authorities told NBC News that Prince was found with prescription painkillers in his possession when he died.
Local authorities have enlisted the help of the Drug Enforcement Administration and the U.S. Attorney's Office in the investigation. The DEA will help determine the origin of the medication and what prescriptions the singer had obtained, the U.S. Attorney said.