UPDATE: Minnesota medical examiner: Prince died of accidental overdose of powerful painkiller fentanyl

MINNEAPOLIS (AP) — Prince died of an accidental overdose of the powerful painkiller fentanyl, autopsy results released today show.

The 57-year-old singer was found dead April 21 at his Minneapolis-area estate.

According to a one-page report released by the Midwest Medical Examiner's Office, Prince administered the drug himself, but the date he took it was unknown. The office said it has completed its death investigation and had no further comment.

Fentanyl is a synthetic opioid, 50 times more potent than heroin, that's partly responsible for a recent surge in overdose deaths in some parts of the country. It also has legitimate medical uses. More than 700 fentanyl-related overdose deaths were reported to the Drug Enforcement Administration in late 2013 and 2014.

The findings confirm suspicions that opioids played a role in the musician's death. After he died, authorities began reviewing whether an overdose was to blame and whether he had been prescribed drugs in the preceding weeks.