The radio call came in just after 1 a.m. to the air traffic control tower at the Quad City International Airport in eastern Illinois.
FOR THE RECORD
10:13 p.m.: A previous version of this article said the location of the Quad City International Airport is in eastern Illinois. It is in western Illinois.
A private jet needed to land, and quickly. A man onboard was unresponsive.
Firefighters and paramedics responded and met the Dassault Falcon 990. They spent 18 minutes attending to the man on the tarmac, before whisking him to a local hospital.
The man was Prince, flying home to Minnesota after back-to-back concerts in Atlanta — which were to be his final moments on stage.
His brief hospitalization in Moline, Ill., on April 15 took place just six days before he was found dead Thursday at his Paisley Park estate in a suburb of Minneapolis.
The cause of death may not be determined for weeks, authorities said Friday. There were no immediate signs of trauma or indications of suicide, and one of the key aspects of the investigation will be his medical history, including previous hospitalizations and any drugs found in his body at the time of his death.
The initial autopsy was completed Friday, but results from tissue sample tests and toxicology screens could take "days... and most likely weeks," said Martha Weaver, a spokeswoman for the Midwest Medical Examiners, during a news conference in Chaska.
On Friday, new details emerged about the final hours of a star — notoriously private, and devoted to a vegan lifestyle — at his sprawling residential complex and recording studio in Chanhassen, about 20 miles southwest of Minneapolis.
But many questions remain. An unconfirmed report from the news site TMZ said the singer was treated for an overdose of Percocet, a painkiller, when his jet diverted to the Quad City airport a week earlier.
Prince, 57, was last seen alive at 8 p.m. Wednesday, when someone dropped him off at Paisley Park, authorities said during the news conference. Prince was apparently left alone that night, without staff members or security.
Prince was "a very private person," said Carver County Sheriff Jim Olson. "I don't think it would be unusual, for him to be there by himself."
When members of his staff couldn't reach him Thursday morning, they went to Paisley Park.
An employee found the singer unresponsive in an elevator on the first floor of the building. A transcript of a 911 call released by the sheriff's department provides a hint of the frantic scramble that followed.
"Yeah, we need an ambulance right now," a man told a 911 dispatcher. "Um, we're at Prince's house.... The person is dead here."
The caller said he didn't know the address of Paisley Park and apologized for the delay, saying everyone with him was "just distraught."
The dispatcher asked: "Are you with the person who's — "
"Yes, it's Prince," the caller responded.
Sheriff's deputies arrived at Paisley Park at 9:43 a.m. Olson said he did not recall seeing a phone in the elevator or a cellphone near the body.
Prince was pronounced dead at 10:07 a.m., but the time of death is still under investigation. He did not appear to have died in the minutes before officials arrived, Olson said.
"We have no reason to believe at this point that this was a suicide," he said. "But again, this is early on in this investigation."
Earlier this month, Prince postponed several shows, and his spokeswoman told reporters that he had the flu. But he returned to the stage, performing in Atlanta twice in one night on April 14, the night before his flight back to Minneapolis.
Unconfirmed reports from the news site TMZ indicated that Prince was treated for an overdose of the painkiller Percocet after the emergency landing. His jet took off again a few hours later.
Doctors typically prescribe Percocet for severe pain, said Dr. Damon Raskin, the chief medical advisor at the drug rehabilitation center Cliffside Malibu. It's considered a high-risk drug, and doctors cannot call a prescription into a pharmacy, but rather must write a prescription on paper or electronically transmit it using a secure system.
"Percocet is in the same family as heroin and codeine," Raskin said. "It's as dangerous as any opiate if someone is not used to it or if they take too much."
The most common cause of death in an opiate overdose is that the user stops breathing, Raskin said, at which point doctors would administer a reversal agent called Narcan.
Olson said officials used CPR, but not Narcan, in an attempt to revive Prince.
In addition to examining medical records and interviewing the singer's inner circle, Olson said, it would be "normal protocol" to review video footage from a drugstore that Prince had reportedly visited in his final days. Olson said the sheriff's department would also file a search warrant for the Paisley Park property within the next 10 days.
Deputies had responded to Paisley Park before, Olson said, but not for Prince. The singer was well-known for hosting concerts and gatherings at the low-slung complex with purple lighting, surrounded by a black fence.
His death resonated around the world, but his passing will also be felt locally, Minnesota officials told reporters.
"To you, Prince Rogers Nelson was a celebrity," Olson said. "To us, he was a community member, and a good neighbor."
Hundreds of mourners, many of them wearing purple, gathered there Friday afternoon. The black chain-link fence that surrounds Paisley Park had been festooned with dozens of purple balloons and bouquets of flowers — and even a purple map of Minnesota.
At what is believed to be his final Paisley Park party on Saturday, Prince briefly appeared, showing off a new Yamaha piano and a purple guitar, according to two guests.
Prince struggled slightly to lift the guitar case onto the piano, but François Vozel, 35, said it could have been because Prince was only 5 foot 2, and the case was unwieldy. Prince didn't look unwell, Vozel said: "He was a few feet away from us. He looked 40 years old."
He sat at the piano, leaving the audience wondering whether he would play — which he did. Just not one of his classics. "It was 'Chopsticks,'" Brendan McGillicuddy, 35, a University of Minnesota doctoral student. "It felt like this tease.... He gets up and he's laughing."
Prince improvised on the piano for two or three more minutes, but didn't play any of his hits, and didn't sing.
He also joked about his hospitalization a day and a half before, telling the partygoers that one of his bigger, sunglasses-clad bodyguards was "the doctor taking care of me," said Vozel. He told the audience that he had been feeling unwell during his Atlanta show.
Prince soon got up to leave, but not before telling his audience: "Save your prayers for a couple of days." Vozel and McGillicuddy looked at each other in concern. Prince laughed, and then disappeared.
A few of the audience members stuck around until after 2 a.m. to see whether Prince or other musicians would come out and play a surprise show, as Prince had done so often in the past.
"Every time I went to Paisley Park, every time there's music instruments, somebody will be playing," said Vozel, a regular who has gone to at least five parties there since September.
But that night the band equipment sat unplayed, and everyone went home, for the last time.
Laura J. Nelson contributed to this report from Los Angeles.
Keegan and Winton reported from Los Angeles and Pearce from Chanhassen.