Source: Prince Probe Looking at Doctor's Role

Investigators suspect an overdose of prescription drugs caused Prince's death last week and they want to find out exactly where he got them, according to a source close to the investigation. The probe is looking at whether a doctor was on Prince's plane when he made an emergency landing in Illinois the week before his death, and whether he overdosed on the plane, a law enforcement official tells the AP, which notes that the development is worryingly reminiscent of Michael Jackson's death. The source confirmed reports that the opiate painkiller Percocet is believed to have been involved. Documents released on Thursday signal that the investigation is now a criminal probe and charges are a possibility, the Star Tribune reports.

The documents released by the Carver County, Minn., sheriff's office Thursday include a request to seal the results of a search conducted at Prince's Paisley Park the day he died, Reuters reports. A judge granted the request, which was made on the grounds that "intense media scrutiny" could hamper the investigation or risk injury to innocent people. Carver County Chief Deputy Jason Kamerud declined to comment on reports of drugs found at Prince's home. He tells the AP that contrary to media reports, investigators have not asked the DEA to get involved. "We might contact them to help us, but that hasn't happened," he says. "We don't have the medical examiner's report yet. We don't know to what extent pharmaceuticals could be a part of this." (Prince was given a private send-off last weekend.)