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Paul Gray, Slipknot

Eddie Malluk/WireImage

It wasn't just one thing that led to Paul Gray's untimely demise.

The Slipknot bassist's death at the tender age of 38 was caused by an overdose of morphine and the narcotic painkiller fentanyl, both injectable substances, according to Polk County Medical Examiner Dr. Gregory Schmunk,  who issued a death certificate Friday.

Gray also suffered from heart disease, Schmunk said.

A hypodermic needle and pills were found near Gray's body when he was discovered by an employee in his room at TownePlace Suites in a suburb of Des Moines.

The coroner has determined that the pills did not contribute to his death.

Investigators also did not find evidence that Gray had prescriptions for either the morphine or the fentanyl. Urbandale Police spokesman Sgt. Dave Disney said it's possible the charges could be filed in the case at some point, but he gave no further information.

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