The documents said detectives were "made aware by witnesses that were interviewed, that Prince recently had a history of going through withdrawals, which are believed to be the result of the abuse of prescription medication".
Police were summoned to the artist's Paisley Park estate after he was found dead in an elevator on the morning of April 21, 2016. Some were in a suitcase labeled with a Prince alias, Peter Bravestrong, along with a page of handwritten lyrics to the 1987 hit "U Got the Look". No one has yet been arrested in connection with Prince's death.
Much of the investigation appears to focus on Kirk Johnson, a bodyguard and friend of Prince's since the "80s and, according to the investigators, "one of the few people who had unrestricted access to Paisley Park".
Carver County investigators and the DEA learned that Prince Rogers Nelson had no prescriptions issued to him and that Kirk Johnson had only one, oxycodone, which was prescribed on April 14 by Dr. Schulenberg, the same doctor who was at the scene of Paisley Park the day Prince died.
A medical expert who predominantly treated Prince, named Doctor Michael Schulenberg, has reportedly admitted to prescribing the singer Oxycodone shortly before he reportedly overdosed on his private jet, which came nearly one week prior to his death.
Messages left with attorneys for Schulenberg and Johnson weren't immediately returned Monday. Schulenberg said he placed the prescription under Prince's bodyguard's name, the documents state.
Prince, who was 57, died from a self-administered, accidental overdose of the drug Fentanyl - an extremely potent, synthetic opiate.
The documents said Prince did not have any prescriptions, including for fentanyl. The agency's website on Monday listed no disciplinary or corrective actions taken against the doctor. If questions remain six months from now, however, he said he'd question what law enforcement is doing. Some pills in other bottles were marked "Watson 853", a label used for a drug that is a mix of acetaminophen and hydrocodone, another opioid painkiller.More news: Srinagar By-Polls: 2% Voters Turned Up For Re-Polling, Counting Today
Investigators have said little about the case over the a year ago, other than it is active.
Although they can resort to subpoenas, the targets can exercise their right against self-incrimination and the only way to get them to talk after that is by offering immunity.
That some Prince confidants or doctors haven't been interviewed shouldn't necessarily raise red flags, Pissetzky said.
Two Los Angeles attorneys say it happens all the time in Hollywood. The Kornfelds' attorney, William Mauzy, has said Andrew had meant to give the medication to a doctor.
Court documents detail that autopsy determined Prince died of a Fentanyl overdose, yet it didn't specify exactly when and where he took the fatal dose or how he obtained it.
"They would be indicting every pharmacist in Beverly Hills if this were strictly enforced", Garofalo said Monday.
"Say you have a major male actor who has a prescription for Viagra, do you want that out on TMZ?"