The revelation that some pills found at Prince's home were counterfeit and contained the powerful synthetic drug fentanyl strongly suggests they came to the music superstar illegally, experts have claimed.
Authorities have so far revealed little about their investigation into Prince's death in April but former prosecutors and defence lawyers who are familiar with drug investigations say it is likely someone will be prosecuted, whether or not the Purple Rain star knew he was taking illegal drugs.
Prince, 57, was found collapsed in a lift at his Paisley Park estate in Minnesota on April 21 and died of an accidental fentanyl overdose.
An official close to the investigation said some of the pills found at the compound were falsely labelled as a common generic painkiller, but actually contained fentanyl.
The official also said that records show Prince did not have a prescription for any controlled substances in Minnesota in the last 12 months.
The only way to get fentanyl - a synthetic opioid that is 50 times more powerful than heroin - is through a legal prescription, or illegally from the black market, according to Joe Tamburino, a Minnesota defence lawyer.
"When you have weird stamped pills in aspirin bottles, sometimes things are what they seem, which is illegally-obtained controlled substances," he told the Associated Press. "How he got them. Who knows?"
Tamburino, who is not connected to the Prince case, said investigators would probably talk to those close to Prince, and also search his and his associates' computers, phones and communications to see whether the pills were purchased online.
"This is not to say the people close to him are guilty - we have no idea of that. But that's where it would start," Tamburino said. He also added that investigators were probably looking at security footage from Paisley Park, if any exists, to see who might have been going to and from the studio.
Gal Pissetzky, a defence lawyer in Chicago, said there were many ways Prince could have obtained the drugs - from a close adviser or friend, a dealer on one of the stops he made as he was on tour, or over the internet himself. He added that investigators might also use mobile phone data to track Prince's whereabouts.
If someone gave Prince the drug that killed him, that person could face a third-degree murder charge, punishable in the state of Minnesota by more than 12 years in prison, Tamburino said.
In addition, any illegal operation that involved making and dealing fentanyl could open many people up to a host of drug charges, from trafficking to conspiracy. Because the sale resulted in Prince's death, it would increase the chances that someone could get the maximum sentence of life in prison if convicted, according to Phil Turner, a former federal prosecutor in Chicago.
Turner said he believed there was a good chance someone would eventually be charged. Improved forensics tools, including the ability to use narcotics' chemical signatures to narrow down possible manufacturers, also increase the chances of arrests.
Pissetzky said news of the falsely labelled drugs told him that the pills did not come from a doctor.
"There's a big, big black market for counterfeit drugs. When people buy these, they don't personally know, many times, that they are not the real thing, and that's when you get overdoses," he said.