MINNEAPOLIS (AP) – A law enforcement official says investigators are looking into whether Prince died from an overdose and whether a doctor was prescribing him drugs in the weeks before he was found dead.

The official told The Associated Press on Thursday that among the things investigators are looking at is whether a doctor was on Prince’s plane when it made an emergency landing in Illinois less than a week before the musician died.

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

The official said investigators are also looking into what kind of drugs were on the plane and at Prince’s house in suburban Minneapolis.