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. Nearly six weeks after he was found dead at his Minneapolis estate, public reports revealed that the cause of Prince’s death was an accidental overdose of fentanyl, but many details in the toxicology reports were still kept from the public.

Now, in an updated and more detailed toxicology report obtained and outlined by the Associated Press, it has been revealed that “exceedingly high” amounts of the synthetic opioid were found in Prince’s blood, liver, and stomach, which undoubtedly killed him. Prince suffered from chronic pain, so he took fentanyl—which the Associated Press notes is “50 times more powerful than heroin”—to deal with it. But the amount found in his body was absolutely deadly, according to Dr. Lewis Nelson, a chairman of emergency medicine at Rutgers New Jersey Medical School.

Details of the report reveal just how “exceedingly high” these quantities were and how deadly the narcotic can be, even if prescribed to treat severe pain. In Prince’s body, there was 67.8 micrograms of fentanyl per liter of blood; many deaths have occurred at just three micrograms per liter of blood. In addition, his liver contained 450 micrograms of fentanyl per kilogram, well over the level of what would be considered cause for “fatal toxicity,” which includes any amount of fentanyl over 69 micrograms per kilogram. The report suggests that Prince took the painkillers orally—hence the fentanyl in his stomach—which then circulated throughout his liver and blood before he died.

About a year after Prince’s death, pill bottles that were found around his home in Paisley Park tested positive for fentanyl, according to lab reports obtained by the Associated Press. The results suggest he may have been prescribed the painkillers and eventually built up a tolerance to the drug over time, leading to his overdose and death. However, the source of the drugs has yet to be discovered, and prosecutors are working to decide if they have a case to press charges against any particular individuals.

Related: See Rare Photographs of Prince Before He Was Prince, and Just 19 Years Old