MINNEAPOLIS (AP) — A law enforcement official tells The Associated Press that investigators are looking into whether Prince died from a drug overdose and whether a doctor was prescribing him drugs in the weeks before his death.

The official says that among the things investigators are looking at is whether a doctor was on a plane that made an emergency landing in Illinois less than a week before Prince died.

The law enforcement official has been briefed on the investigation and spoke on condition of anonymity because he was not authorized to speak to the media.

The official says investigators are also looking into what kind of drugs were on plane and at Prince's house in suburban Minneapolis where the musician was found dead April 21.

Meanwhile, a memorial mural to Prince has been restored on the bluff rock that towers over a Mississippi River town.

The rock has been Red Wing's unofficial billboard over the years. After Prince died last week, the rock was painted with his symbol, the year 1999 and a big red 16.

The city has always had a policy that if someone objects to the art on the rock, city crews will paint over it. The Star Tribune says that's what happened most recently when crews were summoned to paint over the Prince memorial.

Red Wing Mayor Dan Munson, after watching Prince's movie "purple Rain" Wednesday night, was inspired to post a request on social media to have the Prince mural recreated.

Painters Joe Gibart and Brian Paton worked through the night to make that happen.