The musician's death is still under investigation, but there were no obvious signs of trauma on his body
There is "no reason to believe" that Prince's death at the age of 57 was suicide, police have said.
The pop superstar, real name Prince Rogers Nelson, was found dead at his home in suburban Minneapolis, Minnesota, on Thursday.
Giving an update on the latest in the police investigation into the singer-songwriter's death, Carver County Sheriff Jim Olson said there were no signs of trauma on Prince's body when he was found unresponsive in an elevator at his Paisley Park estate.
He 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."
However, he said it was "still under investigation" whether foul play was involved.
He refused to comment on reports that 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.
Celebrity news website TMZ reported that he had overdosed on a drug called Percocet when his jet made an emergency landing in Atlanta, Georgia, on 15 April, six days before his death.
Sherrif Olson whose deputies responded to an emergency medical call at Prince's compound said his officers carry a medication that can be given to someone suffering a drug overdose, but did not use it during the call.
Quoting multiple sources, the website said he left hospital against the advice of doctors.
Prince was taking the drug for a hip problem after having corrective surgery around six years ago, TMZ said.
He had cancelled two shows because of ill health in the run-up to his death.
Prince had spoken about struggling with childhood epilepsy, and friends said he had hip trouble.
His former percussionist Sheila E told the Associated Press news agency that the star suffered the effects from years of jumping off risers and speakers on stage while wearing high heels.
A post-mortem examination was completed earlier on Friday, where information about Prince's "medical and social history" was gathered, the Midwest Medical Examiner's Office said.
Prince's body has now been released to his family, although officials have said a cause of death may not be made public for weeks.
He was last seen at 8pm the night before his death when he was dropped off at his estate, Sheriff Olson said.
The singer had been alone at the estate and staff members had been unable to reach him.
Sheriff Olson added there had been no previous calls to the county sheriff involving Prince at his estate in the last year.