Closing a two-year investigation into how the singer obtained the painkiller – which is 50 times stronger than heroin – a Minnesota prosecutor said there was no reliable evidence to show who had given him the drug.
Carver County attorney Mark Metz said: “We simply do not have sufficient evidence to charge anyone with a crime related to Prince’s death.”
The Purple Rain singer was 57 when he was found alone and unresponsive in a lift at his Paisley Park home in Minnesota on 21 April, 2016.
While Mr Metz acknowledged that someone around the musical icon must have supplied him with the counterfeit pills, he said: “Suspicions and innuendo are categorically insufficient to support any criminal charges.”
Evidence showed Prince thought he was taking Vicodin, not the more potent fentanyl that killed him.
Mr Metz went on to say there was “no evidence that the pills that killed Prince were prescribed by a doctor” and that there was no way of knowing “who else may had a role in delivering the counterfeit Vicodin to Prince”.
Meanwhile, Minnesota doctor Michael Todd Schulenberg, who was accused of illegally prescribing opioids to Prince a week before his death, has agreed to pay $30,000 to settle a federal civil violation.
He had given pills to the musician by making out prescriptions to drummer and long-time friend of Prince, Kirk Johnson.
The doctor’s settlement made no mention of the Prince inquiry and he is not facing criminal charges.
Hundreds of different painkillers were found at the artist’s home during the investigation.
Prince, who projected a public image of clean living and followed a vegan lifestyle and rarely drank alcohol was understood to have suffered from severe pain for a number of years.
Days before his death, he had became unwell during a flight, forcing his private jet to make an emergency landing in Illinois.
More than 42,000 people in the US died from opoiod overdoses last year, while 2.1 million others abused them, according to the Department of Health and Human Services.