Music legend Prince was killed by an overdose of the powerful painkiller fentanyl, Minnesota health officials confirmed.
The 57-year-old singer was found dead April 21 in an elevator of his Paisley Park Studios in Chanhassen, Minnesota, when an employee of a drug rehab in California arrived to see him.
A Prince representative had contacted the rehab, Recovery Without Walls, the day before about a "grave medical emergency" related to the use of prescription pain pills, the facility's attorney later told reporters.
The rehab doctor, Howard Kornfeld, dispatched his son, who is not a physician, to Minnesota with the goal of evaluating Prince and getting him to enter treatment, the lawyer said.
The son was carrying with him a drug that is often used for opioid withdrawal, but when he got to Paisley Park, he and staff members found Prince unresponsive. An ambulance rushed him to the hospital, where he was pronounced dead.
Six days earlier, Prince was briefly hospitalized in Illinois after his plane made an unscheduled stop. His representatives said he was suffering from the flu, though audio from air traffic controllers later revealed the pilot reported an "unresponsive passenger."
Prince's death sparked a multiagency investigation that includes the Drug Enforcement Administration and the U.S. Attorney's office in Minneapolis.
Another doctor who had been treating Prince before his death, geriatrician Michael Schulenberg, was named in a search warrant.
According to court documents, Schulenberg had seen Prince the night of April 20 and went to Paisley Park the following morning to deliver test results only to discover his patient had died. He told police he had prescribed medication to Prince, but the documents did not specify which medication.
Before the disclosures about his medical issues, close friends of Prince said they did not believe the musician — a devout Jehovah's Witness and proponent of clean leaving — was abusing drugs.
But a lawyer who had represented two of Prince's half-siblings told NBC News that his clients — who are now dead — confided in him more than decade ago that the singer had used the painkiller Percocet and cocaine.
"He used drugs not for kicks — he used drugs because it helped him to overcome stage fright," Padden said.
Others have pointed out that Prince had hip problems from years of energetic performances that could have pushed him to take pain medicine.
Dr. Mark Willenbring, who heads the Alltyr clinic in Minneapolis, said that if Prince had been sought help at a local clinic and been treated with a drug like Suboxone — similar to the drug the rehab doctor's son brought with him — he would likely still be alive.
He wondered if fear of being exposed had stopped the singer from reaching out to an addiction specialist.
"Because Prince was Prince he didn't get good care," Willenbring said.
Tracy Connor contributed. This article originally appeared on NBCNews.com.