Carver County Sheriff Jim Olson said during news conference that the investigation was ongoing, but that there were no obvious signs of trauma on the body and "we have no reason to believe this was a suicide." He said the 57-year-old musician was last seen around 8 p.m. Wednesday, about 12 hours before he was found dead.
Despite his debauched stage presence and erotically charged music, Prince had a reputation for clean living and an ability to put on shows that were electrifying in their athleticism.
But after his death - following a series of canceled shows, a reported emergency plane landing for medical treatment and a subdued hometown appearance - questions are being raised about whether he was hiding health problems from his fans.
An autopsy was completed Friday to determine what caused the death of the "Purple Rain" superstar, though officials said it could take days or weeks before results are released. Prince was found unresponsive in an elevator on the first floor of his Paisley Park compound in suburban Minneapolis and could not be revived, sheriff's officials said.
PHOTOS: Prince through the years
Prince had spoken about struggling with childhood epilepsy, and friends said he had hip trouble. His former percussionist, Sheila E., told The Associated Press that Prince suffered the effects from years of jumping off risers and speakers on stage while wearing high heels.
"There was always something kind of bothering him, as it does all of us," she said. "I hurt every single day. You know we're like athletes, we train, and we get hurt all the time. We have so many injuries."
Despite problems with his hip and knee, Prince "kept doing it because he loved doing it and it was something no one was doing," she said.
Prince's cousin Chazz Smith said he could not comment on reports about Prince's health and would not say when he last saw his cousin.
"I can tell you this: What I know is that he was perfectly healthy," said Smith, who formed a band with Prince when they were kids.
Smith said Prince swore off drugs and alcohol as a kid, and the group they played with saw a lot of music greats fall, so "we decided to never get into that stuff, and no one did."
Minnesota authorities declined at the Friday news conference to say what may have been taken from Prince's home after his death, or to discuss a report that the musician suffered a drug overdose less than a week before he died.
Carver County Sheriff Jim Olson and a medical examiner's office spokeswoman refused to comment Friday when asked about prescription drugs or a possible overdose. Celebrity website TMZ.com, citing "multiple" unnamed sources, has reported that Prince received treatment for a painkiller overdose while traveling home from concerts in Atlanta last week.
TMZ also cited unidentified sources in reporting last week that Prince fell ill as he returned to Minneapolis early on April 15, and that his flight made an emergency landing in Moline, Illinois, where he was briefly hospitalized.
Asked whether Prince's flight made such a landing at the Quad City Airport in Moline, public safety manager Jeff Patterson said Friday that a private Falcon 900 plane made a "medical diversion landing" at 1:17 a.m. that day. He said the plane requested an ambulance at the airport and a patient was taken to the hospital.
Patterson would not identify the patient or the plane's owner, or provide the aircraft's tail number.
Representatives for Prince have not responded to requests from The Associated Press for comment on the reports.
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The singer's death came two weeks after he canceled concerts in Atlanta, saying he wasn't feeling well. He then played a pair of makeup shows April 14 in that city, apologizing to the crowd shortly after coming on stage.
At one point early in his first show he briefly disappeared from the stage without explanation. After about a minute he returned and apologized, saying he didn't realize how emotional the songs could be. He played the rest of the show without incident, repeatedly jumping up from the piano and pacing around the stage between songs, and performed three encores.
In the later show, Prince coughed a few times, though the show was again energetic.
Then came the reported emergency landing en route to Minnesota. The night after that, Prince hosted a dance party at Paisley Park, where some fans said he looked fine and seemed irked by reports of an illness. "Wait a few days before you waste any prayers," he said.
But by his high-energy standards, it was a subdued appearance. Prince didn't play except to tap out a few notes on a new purple Yamaha piano, and lingered only for a few minutes before disappearing.
Prince was slated to perform a surprise set of shows earlier this week in St. Louis but canceled last week because of health concerns, a promoter said.
Promoter Steve Litman said Friday that he had been working for weeks to set up two surprise pop-up shows on April 18 at the Fox Theatre in St. Louis. Litman said that tickets were set to go on sale April 15, but that Prince's representatives told him on April 14 that Prince needed to back out because of concern he might have to cancel as a result of illness.
Prince disclosed in a 2009 interview with Tavis Smiley that he was born an epileptic and had seizures when he was young. It was unclear if his epilepsy carried into adulthood.
In 2009, Prince, a Jehovah's Witness, he told an interviewer with the Los Angeles Times that he didn't do drugs "or I'd give you a joint" to share while they listened to music.
Heather McElhatton worked on and off as a set decorator for Prince's video shoots at Paisley Park from 1988 to 1998. She said she never saw Prince take drugs or drink during her time there.
"I never saw him use a single drug, ever, but he did have a lot of energy. He could shoot for two days straight," McElhatton said Friday. "Was it natural energy? Was it augmented energy? I don't know. I never saw him eat."
Sheila E. said that's the man she knew, too.
"It's just like being a football player and a basketball player. You know he really took care of himself. He ate well. He ate better than me," she said.
She said she hadn't talked to him for at least six months but tried to reach him after reading reports that he needed emergency medical attention. She said the man who answered told her Prince was sleeping and would let him know she called.
"He said he was good," she said.