Prince had “exceedingly high” levels of the opioid fentanyl in his body at the time of his death, a toxicology report from his autopsy has revealed.

The 57-year-old singer died on 21 April 2016, in an elevator at his Paisley Park estate in Minnesota. Public data released six weeks after his death showed he passed away following an accidental overdose of fentanyl – a drug which is 50 times more powerful than heroin – but now a toxicology report has shed light on new details.

According to the report, obtained by the Associated Press (AP), Prince had 67.8 micrograms of fentanyl per litre of blood at the time of his death. It adds that deaths have been reported in people who have had blood levels ranging from three to 58 micrograms of fentanyl per litre of blood.

The report continues to reveal that Prince had 450 micrograms per kilogram in his liver – noting that concentrations greater than 69 micrograms per kilogram in the liver “seem to represent overdose or fatal toxicity cases”.

It was also found that the Purple Rain star had a lethal amount of fentanyl in his stomach. Dr. Charles McKay, president of the American College of Medical Toxicology, who was not involved in the collating of the report, told AP that the findings suggest Prince took the drug orally. Dr. McKay added that the fact the singer had fentanyl in his blood and liver mean the drug had time to circulate around his body before he died.

Dr. Lewis Nelson, Chair of emergency medicine at Rutgers New Jersey Medical School, also not connected to the Prince investigation, said of the findings: “The amount in his blood is exceedingly high, even for somebody who is a chronic pain patient on fentanyl patches.”

Referring to the fentanyl concentrations in Prince’s body, Dr. Nelson called them a “pretty clear smoking gun”.

It remains to be seen whether or not any wrongful death lawsuit is filed in relation to Prince’s passing.

The singer was known to have been suffering from a longtime hip problem, but did not have any known prescriptions for fentanyl issued to him leading up to his untimely passing.