Prince died from an accidental overdose of a powerful opioid, according to autopsy results released Thursday.

The Midwest Medical Examiner's Office report lists the cause of death as an accident, the result of self-administering the drug fentanyl.

Fentanyl is a synthetic opiate that's more powerful than morphine, according to the National Institute on Drug Abuse.

"It is typically used to treat patients with severe pain, or to manage pain after surgery," according to the NIDA. "It is also sometimes used to treat people with chronic pain who are physically tolerant to opiates."

The legendary artist was found dead in his Minneapolis suburban home on April 21, at the age of 57. The Midwest Medical Examiner's Office conducted an autopsy and ran the toxicology exam. The medical examiner's office has completed its "death examination," though the Carver County Sheriff's Office is continuing its own investigation.

Carver County Sheriff Jim Olson said in April that the initial investigation into the legendary musician's death showed "no obvious signs of trauma."

The U.S. Attorney's Office in Minnesota and the Drug Enforcement Administration are also involved in the investigation.

On the morning that Prince's body was found inside of an elevator, a doctor who had treated the superstar on April 7 and April 20 arrived at Paisley Park to deliver test results, according to a search warrant obtained by the Los Angeles Times and the Minneapolis Star Tribune. Court documents, which have since been sealed, do not describe the test results.

Michael Todd Schulenber, who told investigators he was a doctor at the North Memorial Medical Center, "appeared on the death scene" in Chanhassen, Minn., on April 21.

The pop icon's death came a day after his representatives contacted a California pain and addiction specialist for help, sources told the Star Tribune. Dr. Howard Kornfeld, who couldn't immediately travel to Minnesota, sent his pre-med student son to meet with Prince and a Minnesota doctor, the newspaper reported.

Pharmaceutical fentanyl is approved to treat severe pain, usually from advanced cancer, and is 50 to 100 times more potent than morphine, according to the Centers for Disease Control and Prevention.

Many fentanyl overdoses involve illegally made versions of the drug. In these cases, heroin or cocaine is laced with fentanyl to increase its potency — something that authorities have said is increasingly happening and fueling the opioid addiction crisis.

Deaths from prescription opioids and heroin set a record in 2014, with deaths involving powerful synthetic opioids such as fentanyl rising by more than 80 percent from the previous year.

About 5,500 people died in 2014 from overdoses involving synthetic opioids, according to the CDC.

The singer, born Prince Rogers Nelson, performed in Atlanta a week before he died. Following the show, his private jet had to make an emergency landing in Illinois because of an "unresponsive passenger," records show. Prince's bodyguard had to carry him off of the plane.

Prince was reportedly hospitalized; at the time, media reported the entertainer had been battling the flu. The Minneapolis Star Tribune, citing two sources close to the artist, reported that he was back home by that evening.

Prince held a party the following night at Paisley Park, where he made a brief appearance. Regarding his reported health scare, he told the crowd "wait a few days before you waste any prayers."

This post has been updated.