Not a book, but the story of the schizophrenic killer Herbert Mullen.
The first person account of his killings is beyond the blackest of black comedies. He inadvertently killed two people who "volunteered" who lived just down the road from each other, they both happened to be drug dealers and the cops thought it was a drug deal gone bad sort of thing…Herbert Mullin, 25. Although he had been institutionalized and evaluated as a danger to others, he'd nevertheless become an outpatient, which allowed him to roam freely. He'd stopped taking his antipsychotic medication and "heard" a voice that urged him to kill. It was his mission, Mullin believed, to save the people of California from a super-earthquake that would send it into the ocean. Thus, he decided that he had to "sing the die song," which he believed would persuade thirteen people to either kill themselves or allow themselves to become human sacrifices (which he said they conveyed to him telepathically). Using a knife, gun, or baseball bat to slay those he selected, he killed until police picked him up.
