A doctor prescribed Prince the painkiller oxycodone under the name of Kirk Johnson, his longtime friend, and associate.
Dr. Michael Todd Schulenberg told authorities he wrote the prescription under Johnson's name for privacy purposes, according to a search warrant that was among the unsealed documents.
The documents also show that authorities searched Prince's Paisley Park home in Chanhassen, Minnesota, trying to determine how he got the fentanyl that killed him.
Prince, who was 57 at the time of his death, was found unresponsive in an elevator at his Paisley Park home on April 21, 2016. The oxycodone Schulenberg prescribed was not listed as a cause of Prince's death.
The medical examiner's office said Prince died of an accidental overdose of the opioid fentanyl.
Investigators, however, found pills labeled "Watson 853," which is an imprint used for a drug that is a mix of acetaminophen and hydrocodone.
Last August, a source familiar with the investigation told the Minneapolis Star Tribune that pills seized from Prince's home were marked as hydrocodone but contained fentanyl.
Documents unsealed Monday also revealed that authorities found a pamphlet for an addiction recovery center in California inside the pop star's home. Prince's staffers had contacted addiction specialist Dr. Howard Kornfeld the day before he died, trying to get him some help.
Kornfeld sent his son, Andrew, to Minnesota that night. The younger Kornfeld was sent to help evaluate Prince's health and encourage him to get treatment, but instead and he was among those who discovered Prince's body.
The documents also noted that some of the drugs were found in a suitcase labeled "Peter Bravestrong." Authorities said they suspect that was an alias Prince used while traveling. Although the documents shed light on Prince's battle with addiction, it remains unclear where he got the drug that killed him.
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