MINNEAPOLIS (AP) — Nearly a year after Prince died from an accidental drug overdose in his suburban Minneapolis studio and estate, investigators still don't know how he got the fentanyl that killed him.

An official with knowledge of the investigation told The Associated Press that authorities still haven't interviewed a key associate who was with Prince in his final days, and they haven't asked a grand jury to investigate. The official spoke on condition of anonymity because the investigation is ongoing.

Prince was 57 when he was found alone and unresponsive in an elevator at Paisley Park on April 21.

Criminal justice experts say the pace of the investigation doesn't necessarily mean it's in trouble or that no one will be charged. Tracking illegally obtained pills is complex, and prosecutors want to be sure before filing charges.

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