A prison inmate incarcerated to the State Correctional Institute at Houtzdale pled guilty to murder yesterday in Clearfield County Court. 34 year old Derek Bullard was sentenced 10-20 years for killing his cellmate 79 year old Roberto Quevada last June. Bullard reportedly told authorities he choked the 79 year old to death, because voices in his head told him to do so. The new sentence will run consecutive to his current sentence of 12-30 years for endangering the welfare of a child and terroristic threats, in Lehigh County cases that occurred in 2013.