Ever since the legendary musician Prince passed away on April 21, 2016, there has been much speculation about the cause of his tragic and sudden death.

On Tuesday, a toxicology report for the late singer Prince confirmed his body contained an “exceedingly high” level of fentanyl at the time of death. Fentanyl is a synthetic opioid used to manage moderate to severe levels of pain.

“The amount in his blood is exceedingly high, even for somebody who is a chronic pain patient on fentanyl patches,” said Dr. Lewis Nelson, chairman of emergency medicine at Rutgers New Jersey Medical School. He called the fentanyl concentrations “a pretty clear smoking gun.”

The report says the concentration of fentanyl in Prince’s blood was 67.8 micrograms per liter. The report explains that fatalities have been documented in people with blood levels ranging from three to 58 micrograms per liter.