DES MOINES, Iowa – A Des Moines doctor faces involuntary manslaughter charges for allegedly prescribing large amounts of narcotic painkillers to eight patients who fatally overdosed, including a metal band’s founder.

Dr. Daniel Baldi appeared Wednesday in Polk County District Court, and a judge entered a not guilty plea on his behalf, The Des Moines Register reported. Involuntary manslaughter is an aggravated misdemeanor under Iowa law.

One of the eight patients was identified in court papers as Paul Gray, a founder of the band Slipknot. He died of an overdose in 2010 at an Urbandale hotel.