Prince had prescription opioid medication on him and in his home when he died last week, US media reported, although autopsy results have yet to indicate why the pop icon died.

The pills were found both on Prince's person and at his Paisley Park compound, CNN and other media outlets reported Thursday, citing a law enforcement official.

The prescription pills, which are used to treat pain, were discovered "at the death scene," according to the Minneapolis Star Tribune.

The drugs' role in Prince's death is under investigation, The Tribune reported, citing unnamed sources.

The Drug Enforcement Administration has been called in to help with the case, CNN said.

The authorities have said that the pop star was alone at the time of his death, and that they don't believe suicide or foul play was involved.

Investigators are examining whether an overdose of opioids led to his death, and are trying to determine how he got the pills and from whom, The Star Tribune reported, citing sources with direct knowledge of the case.

Individuals with knowledge of an emergency stop made by Prince's plane just days before the star's death said he had overdosed on an opioid at the time, according to the Star Tribune.

He was returning from Atlanta, where he performed what would be his final full-fledged concert.

Paramedics responding to the emergency gave Prince an injection of the opioid antidote Narcan, it said.

The 57-year-old music sensation, one of the most acclaimed and unique artists of his generation, was briefly hospitalized, complaining of flu-like symptoms.

The cause of his death remains unknown.

The authorities have said that at least four weeks would be needed for results of his autopsy, which was conducted before his cremation last week.

On Wednesday, a judge appointed a special administrator to oversee Prince's estate, accepting a request from the pop star's sister.

Prince died leaving no will. He had no children or living parents.

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His sister, Tyka Nelson, who sought Bremer Trust as the special administrator, was named an heir along with five of the "Purple Rain" star's living half-siblings.

Bremer Trust will be tasked with managing Prince's estate as well as determining whether there are additional heirs.

Court officials in Minneapolis scheduled a May 2 hearing at the request of relatives with a claim to Prince's estate.

The extent of the musician's fortune is unclear, with the website Celebrity Net Worth estimating he was worth $300 million.

Prince's heirs will also control his vast vaults of unreleased material, which is said to include entirely unheard albums that were shelved.