By Karen Mizoguchi
March 27, 2018 at 08:21 AM EDT
US singer Prince performs on October 11,
Credit: BERTRAND GUAY/Getty Images

New details about Prince‘s death have been revealed.

A toxicology report from the late singer’s autopsy states the concentration of fentanyl in his blood was 67.8 micrograms per liter according to the Associated Press, which obtained the report on Monday.

Fatalities from the drug — which is estimated to be 80 times as potent as morphine and hundreds of times more potent than heroin — have been documented in people with blood levels ranging from three to 58 micrograms per liter.

“The amount in [Prince’s] blood is exceedingly high, even for somebody who is a chronic pain patient on fentanyl patches,” Dr. Lewis Nelson, chairman of emergency medicine at Rutgers New Jersey Medical School, told the AP.

In addition, the toxicology report states the level of fentanyl in the Prince’s liver was 450 micrograms per kilogram and notes that liver concentrations greater than 69 micrograms per kilogram “seem to represent overdose or fatal toxicity cases.”

“The Midwest Medical Examiner’s Office (MMEO) released all data available to the public regarding the death investigation of Prince Rogers Nelson on June 2, 2016,” the medical examiner said in a statement Tuesday. “Under Minnesota law, all other medical examiner data is considered private or nonpublic data. MMEO has not and cannot release any further information about this case.”

Prince was 57 when he was found dead in his Paisley Park compound on April 21, 2016. The autopsy was completed the next day. In June 2016, the Midwest Medical Examiner’s Office revealed the singer died of an accidental overdose of fentanyl.

Unsealed court documents released in April 2017 revealed that investigators discovered a number of prescription drugs hidden away inside Prince’s famed Paisley Park compound. In addition to the medication, investigators also discovered opioids in multiple areas of Paisley Park and stored in containers other than pill vials, including vitamin bottles.

Fentanyl was also the cause of death for singer Tom Petty, who died on Oct. 2, 2017 at age 66.

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