Morphine OD killed Slipknot bassist

LOS ANGELES, June 21 (UPI) -- An overdose of morphine and the narcotic painkiller fentanyl caused Slipknot bassist Paul Gray's death in May, the Polk County, Iowa, medical examiner says.

Gray was found dead at age 38 at TownePlace Suites in a suburb of Des Moines. Grey was one of three original members of Slipknot, formed in 1995 in Des Moines.

E! Online said the musician's death certificate was issued by Medical Examiner Dr. Gregory Schmunk Friday.

Schmunk also found Gray suffered from heart disease, the Web site said.