Prince’s next scheduled tour dates were two back-to-back shows on April 7 at the Fox Theater in Atlanta. But as she was brushing her teeth around 10 on the morning of the show, Lucy Lawler-Freas, the Atlanta promoter, said she got a call from Mr. Worsoe: Prince was sick with the flu.

“He can barely speak; his voice is really hoarse,” she recalled Mr. Worsoe telling her.
It was the first time in the more than a quarter-century that he had worked with Prince that the artist canceled a show, Mr. Worsoe said.

But two days later, Prince rescheduled the show for the 14th.

On the rescheduled date, Prince landed in Atlanta late day and needed a police escort to make it to the theater on time. He said he was still feeling sick, but back in the dressing room where water and fresh fruit was awaiting Prince, Mr. Worsoe said he did not notice any visible signs of illness.

With his Afro picked out, Prince took the stage, sidling up to his purple piano and surrounded by candelabras. He performed two sets, at 7 and 10 p.m.

“He was epic,” Ms. Lawler-Freas said. No signs of the flu.

Prince said it was his best show ever, Mr. Worsoe recalled. But afterward, Prince said that his stomach hurt. Prince wanted to go back to Minneapolis to get checked out by a doctor, Mr. Worsoe said, and asked to postpone shows in St. Louis, Nashville and Washington that were scheduled, but not yet announced, for the next week.

Midair Medical Crisis

Prince and two other passengers boarded his private jet, which left at 12:51 a.m. Eastern on the Friday after his Atlanta show. Just over an hour in, the pilot radioed to air traffic controllers that he had an unresponsive passenger on board. The plane, only about 48 minutes from its destination of Minneapolis, turned around and quickly landed in Moline, touching down at 1:18 a.m.

Prince’s bodyguard carried him off the plane to emergency responders waiting on the ground, according to city records. They rushed him to a n opioid overdose, according to published reports. But he stayed at hospital. Prince was treated with a Narcan shot, typically administered to those suffering from athe hospital for only a few hours before flying back home.

A master of image control, Prince started shaping the narrative right away.

He hastily organized a party at his home for the following evening. Later, he casually rode a bicycle in a stripmall parking lot.

Prince’s representatives asked Jeremiah Freed, a blogger who runs, to help spread the word of the party on Saturday night. Before that night, Mr. Freed said, he never really had any concerns about Prince’s condition, though he was struck by something that the musician told him in January. Prince spoke of David Bowie’s death, Mr. Freed recalled, saying he was having lucid dreams in which he communicated with people who died.

When Prince first strolled into the party, before he was in full view of the public, “He looked upset to me,” Mr. Freed recalled. They locked eyes, he added. “When I saw him, there was no smile.”

Other friends reached out to Prince over the weekend, concerned about what had happened to him on the plane. He had a resounding message: I’m O.K.

Knowing how much Prince, who didn’t use a cellphone but was constantly surfing his silver MacBook, valued his privacy, friends said they did not press him.

On Monday, April 18, Ms. Lawler-Freas, the Atlanta promoter, said that Prince’s representatives told her to hold off on confirming the eight tour dates she had arranged for him. He was going to take a break that week, and they would get back to her the next Monday, April 25, to confirm the concerts.

Prince seemed to lead a mundane life from there, stopping by a show at the Dakota Jazz Club in Minneapolis on Tuesday, April 19. The next day, police said, someone dropped him off at his compound at about 8 p.m. He was found dead the next morning, setting off the sweeping investigation.

“If we really want to be accurate and get it right, I think you have to pump the brakes,” said Deputy Kamerud of the Carver County Sheriff’s Office. “Some investigations are like 50-piece puzzles, some are like a 10,000-piece puzzle. This one is the latter.”

Mr. Freed, the blogger, said he could hardly believe reports of the painkiller dependency. Prince, he said, would help anyone in his band with a drug problem and even pay the cost of their recovery.

If you abused drugs, he said, “you weren’t going to work with him. You didn’t have a job.”