Opioid painkillers were found in several places at Prince’s Paisley Park home following the pop superstar’s death, according to a police search warrant.
On the day Prince was found dead in his home in Minnesota, several pills labelled “Watson 853”, an hydrocodone-acetaminophen, were found at his property.
The warrants also reveal that some of the pill bottles containing the painkillers had the name Kirk Johnson on them.
Mr Johnson was Prince’s estate manager and long time associate and told investigators that the pop star had been struggling with opiate use.
Just six days before he died, Prince fell ill on a plane and made an emergency stop in Illinois as he was returning home from a concert in Atlanta. First responders revived him with two doses of a drug that reverses the effects of an opioid overdose.
A doctor who saw the pop star in the days before he died had prescribed oxycodone under Mr Johnson’s name to protect the musician's privacy, according to an affidavit.
Oxycodone was not listed as a cause of the 57-year-old’s death and an autopsy showed he died from an accidental overdose of fentanyl, a synthetic drug 50 times more powerful than heroin.
Investigators were told by witnesses that Prince "recently had a history of going through withdrawals which are believed to be the result of abuse of prescription medication", CNN reports.
The documents are part of several affidavits and search warrants unsealed in Carver County District Court as the year-long investigation into Prince's death continues.
They do not reveal where Prince got the fentanyl that killed him but it is thought it was obtained illegally and not by prescription.
Prince was 57 when he was found alone and unresponsive at his Paisley Park home on 21 April.
Agencies contributed to this report