NEW YORK — Prince, the music icon who struggled with debilitating hip pain during his career, died from an accidental overdose of self-administered fentanyl, a type of synthetic opiate, officials in Minnesota said Thursday.

The news ended weeks of speculation about the sudden death of the musician, who had a reputation for clean living but who appears to have developed a dependency on medications to treat his pain.

Authorities have yet to discuss how he came to possess the fentanyl and whether it had been prescribed by a doctor.

Officials had waited several weeks for the results of a toxicology test undertaken as part of an autopsy performed after he was found dead April 21 in an elevator at his estate. He was about to enroll in an opioid treatment program when he died at 57, according to the lawyer for a doctor who was preparing to treat him.

The Midwest Medical Examiner’s Office, which conducted the autopsy, declined to comment beyond releasing a copy of its findings. The Carver County Sheriff’s Office is continuing to investigate the death with help from the federal Drug Enforcement Administration. The sheriff’s office had said it was looking into whether opioid abuse was a factor, and a law enforcement official had said that painkillers were found on Prince when investigators arrived.

“The ME report is one piece of the whole thing,’’ said Jason Kamerud, the county’s chief deputy sheriff.

Fentanyl is a potent but dangerous painkiller, estimated to be more than 50 times more powerful than heroin, according to the Centers for Disease Control and Prevention. The report did not list how much fentanyl was found in Prince’s blood. Last year, federal officials issued an alert that said incidents of overdoses with fentanyl were “occurring at an alarming rate throughout the United States.’’

Weeks before his death, Prince postponed a concert in Atlanta, saying he had the flu. A week later, he made up the show, but on the flight home to Minneapolis he fell unconscious and his private jet made an emergency landing in Moline, Ill. There, emergency medical personnel treated him with Narcan, a drug typically used to counteract the effects of an opioid overdose, according to a law enforcement official briefed on the matter.

Prince told his friends and associates after that emergency that he was OK. His publicist said he had the flu, which was what had led to the emergency landing.

But a concerned friend reached out to a California-based doctor who specializes in treating opioid addictions, in hopes of getting him into treatment, according to William Mauzy, a lawyer for the doctor, Howard Kornfeld.

On April 20, Kornfeld sent his son, Andrew, who is not a doctor but works at his father’s clinic, on a red-eye flight to Prince’s Paisley Park estate in Chanhassen, Minn., Mauzy said. But when Andrew Kornfeld arrived on the morning of April 21, he and two members of Prince’s staff found the singer lifeless. He then called 911.

His death comes amid an opioid addiction epidemic across the United States. Studies showed that more than 28,000 people died from opioids, which include heroin and painkillers, in 2014 and 4.3 million people were taking pain medication for nonmedical purposes that year.

Fentanyl can be consumed in a variety of ways, including through patches, injections, smoking, and a lollipop. It is unclear what method of administration Prince used.

Dr. Torin Finver, an addiction medicine specialist at the Jacobs School of Medicine at the University of Buffalo, said it can be easier to overdose on the drug because its effects last shorter than other opiates, thus leading users to dose more frequently and possibly accidentally consume too much.

The illicit shipment of fentanyl into the United States has become a major concern for federal officials, who say the substance has become an increasingly popular product of drug cartels in Mexico and is often mixed with heroin.

Prince’s body was worn down from decades of taxing performances, in which he often did splits or jumped from heights on platform shoes, several people close to him said. One person who knew him said that Prince had hip surgery in the mid-2000s, but it did not completely alleviate his pain.

To some of Prince’s closest friends, his struggle with pain medication came as a surprise because the musician had become a Jehovah’s Witness and strove, friends said, to live such a clean life. He was averse to drinking alcohol and frowned on the use of recreational drugs. He typically ate a vegan diet and would not allow meat in his house.

Investigators have used search warrants as they look for evidence in the case and collected records from medical personnel who treated him in the final months of his life, including one Minnesota doctor, Michael Schulenberg, who had seen him the day before he died.

It was unclear what Schulenberg saw Prince for, but he had also seen him weeks earlier, the same day that Prince had postponed the Atlanta show. Schulenberg also prescribed medications for Prince, according to an affidavit filed by an investigator in support of a search warrant, though it did not specify the drugs.