Authorities have "no reason to believe" Prince took his own life and there were "no obvious signs of trauma" on the his body, US police said.
The music superstar died at his Paisley Park estate near Minneapolis on Thursday after he was found collapsed in a lift. He was 57.
Speaking at a press conference at Carver County Courthouse in Chaska, Minnesota, Sheriff Jim Olson refused to comment on reports that Prince had been taking a powerful painkiller before his death.
He said it was "still under investigation" whether foul play was involved.