Word from authorities that Prince died of an overdose of fentanyl, a powerful opioid that is up to 50 times more potent than heroin, is far from the end of the investigation. In some ways it's just the beginning.
After Thursday's announcement about the superstar's death, investigators in the months to come will try to determine whether the singer had a prescription for the drug or whether it was supplied illegally.
If it's latter, someone could face criminal charges carrying years, or even decades, in prison.
Prince was found dead on April 21 at his Minneapolis estate and longtime friend and collaborator Sheila E told AP that he had intense hip and knee pain from years of performing.
Although the death was formally ruled an accident, that merely signified that it was not intentional and does not preclude a criminal prosecution.
According to a one-page report released by a medical examiner, Prince administered the drug himself on an unknown date.
Fentanyl is a synthetic painkiller. Patients who have built up a tolerance to other prescription painkillers sometimes seek it out, and it is partly responsible for a recent surge in overdose deaths in some parts of the country. The drug was also found in Michael Jackson's home at the time of his death.
Because of its risks, it is tightly controlled by the Food and Drug Administration, but much of it is manufactured illegally.
Legal experts say the focus of the investigation will now probably turn to whether the source or sources of the fentanyl were legal or not.
The superstar had a reputation for clean living, and some friends said they never saw any sign of drug use.
"The investigation may expand to people who surround him," said Gal Pissetzky, a Chicago-based attorney who has no link to Prince. "If fentanyl was obtained illegally, I don't think Prince would have gone out to meet someone in a dark alley to get the substance."
But he said it would be "very, very difficult" to identify a street dealer if they were the source.
Illegally distributing fentanyl to someone who then dies from it is punishable by a mandatory minimum sentence of 20 years under federal law. Under Minnesota law, the same actions can result in third-degree murder charges and up to 25 years in prison.
Prince, 57, died less than a week after his plane made an emergency stop in Moline, Illinois, for medical treatment as he was returning from an Atlanta concert. He was reportedly found unconscious on the plane, and first responders gave him a shot of Narcan, an antidote used in suspected opioid overdoses.
The names of at least two doctors have come up in the death investigation.
Dr Michael Todd Schulenberg, a family practitioner, treated Prince twice in the weeks before his death, including the day before, and prescribed medications for the singer.
Dr Howard Kornfeld, a California addiction specialist, was asked by Prince's representatives on April 20 to help the singer.
Howard sent his son Andrew on a flight that night, and Andrew was among the people who found Prince's body the next morning, according to their attorney, William Mauzy.
They have denied delivering, dispensing or administering any medication to Prince.