According to the report from the toxicology tests done as part of Prince’s autopsy by the Midwest Medical Examiner’s Office, the star died from an accidental overdose of the opioid fentanyl.

Prince Rogers Nelson investigation results attached pic.twitter.com/CMt6lQSGxJ

— Midwest Medical Exam (@MidwestMedExam) June 2, 2016

The drug fentanyl is a synthetic drug, which is prescribed for cancer treatment but has also been used, especially in the past years, as an illicit drug. Fentanyl appears to be responsible for an increase on deaths by overdose. The U.S. Drug Enforcement Administration has reported that fentanyl is 25 to 50 times stronger than heroin and 50 to 100 times stronger than morphine.

The Associated Press states that “more than 700 fentanyl-related overdoses were reported to the Drug Enforcement Administration in late 2013 and 2014.”

It wasn’t reported whether Prince had a prescription for the drug or how he obtained it, however, it was stated that anyone who provided him with the drug illegally could face criminal charges.

Illegally supplying fentanyl to someone who then dies as a result of taking the drug, has a minimum sentence of 20 years in prison under federal law, and up to 25 years in prison under Minnesota law, where it could be viewed as third-degree murder charges.

The report by the Midwest Medical Examiner’s Office is brief and doesn’t offer much detail. Besides a description of Prince’s physical appearance and clothing at the moment of the autopsy, it states, “How injury occurred: The decedent self-administered fentanyl.” For manner of death, a box is marked for “Accident” and for Cause of Death it simply says “Fentanyl toxicity.”

The Office said the investigation about the icon’s death was completed and, thus, had nothing else to comment.

Prince was 57 years old when he died on April 21st. He was found unresponsive in an elevator of his home and studio, Paisley Park, in Chanhassen, Minnesota. The autopsy was conducted the day after Prince’s body was found.