The singer, whose real name was Prince Rogers Nelson, died at his Paisley Park estate near Minneapolis on Thursday after he was discovered collapsed in a lift. He was 57.
Jim Olson, Carver County Sheriff, said there were “no obvious signs of trauma” on Prince’s body and it was “still under investigation” whether foul play was involved.
Speaking at a press conference at Carver County Courthouse in Chaska, Minnesota, the sheriff refused to comment on reports that Prince had been taking a powerful painkiller before his death.
He said Prince was last seen at 8pm the night before his death when he was dropped off at Paisley Park.
The singer had been alone at the estate and staff members were unable to reach him, the official added.
A post-mortem took place on Friday, where “medical and social history” was gathered, the Midwest Medical Examiner’s Office (MMEO) said.
Prince’s body was released to his family but a cause of death may not be made public for weeks, officials said.
Celebrity news website TMZ reported that Prince had overdosed on a painkiller called Percocet when his private jet made an emergency landing in Atlanta, Georgia, on 15 April, six days before his death.
The star was taking the drug for a hip problem after having corrective surgery around six years ago, TMZ said.
A spokeswoman for the MMEO said it would not release information from the post-mortem examination until “all results are obtained” and the findings of a toxicology scan “could likely take weeks”.
Prince was found collapsed in a lift by staff members, the sheriff said.
“There were no obvious signs of trauma on the body at all. We have no reason to believe at this point that this was a suicide.”
Asked whether there was any reason to believe foul play was involved, Olson said: “We have no reason to believe at this time it was a suicide, the rest of it is under investigation.”
He refused to comment on the reports the star had been taking a powerful painkiller before his death, and a medical examiner’s office spokeswoman refused to say whether any prescription drugs were taken from Prince’s home after his death.
There had been no previous calls to the county sheriff involving Prince at Paisley Park in the last year, he added. Three of Prince’s employees were at the scene when police arrived, Olson revealed.
He said Prince was “a very private person” and it would not be unusual that he would be alone.
It was under investigation whether criminal charges would be brought, the sheriff added.
Olson said there were no signs of trauma which he said meant “there were no signs of violence”.
The investigation will include examining any available surveillance video.