Who really knows what evil lurks in the hearts of those who seem so safe and normal? Behind those big smiles, behind the facade they so perfectly hide within, lies their true self; a vicious killer with a taste for blood lust. So was Orville Lynn Majors, a practical nurse from Clinton, Indiana, whose favorite past time was injecting his elderly patients wkith potassium chloride, mainly because the “old farts irritated him.” Some of the hospital residents also testified that they'd heard Majors referring to some of the elderly patients as, “a pain in my ass that needs to be gassed.” He was believed to have killed at least 100 elderly patients between 1993 and 1997, which made him the biggest mass murderer in US history.