In December 1874, at the age of fifteen, Jesse Pomeroy became the youngest person in Massachusetts ever to be sentenced to death. He had, when he was twelve, tortured seven children in his South Boston neighborhood, subsequently mutilating and killing two others. All Pomeroy said in explanation was that he “couldn't help it.” This essay argues that an important cause of Pomeroy's affectless violence was one held by many of his contemporaries but dismissed by later cultural historians: his voracious reading of dime novel westerns. Central to cheap western literature was the formulaic scene of torture practiced by Indians and white renegades. Pomeroy's crimes, as I will describe, strikingly repeated these accounts, and they further disclose his dangerous identification with the unambiguously evil renegade Simon Girty. Moreover, the logic of torture in dime novel westerns – the fact that the torture is promised but never delivered – maps perfectly onto what have been called the “nonfulfilled experiences” central to the fantasies of serial killers. Just as with some horrific crimes of our own era, it seemed as if the mass media – specifically the mass production of repetitive violent images and plots – had indeed played a role in a boy's compulsive violence.