"A sexual sadist, the Zodiac killer took pleasure in torture and murder. His first victims were a teenage couple, stalked and shot dead in a lovers' lane. After another slaying, he sent his first mocking note to authorities, promising he would kill more. The official tally of his victims was six. He claimed thirty-seven dead. The real toll may have reached fifty. Robert Graysmith was on staff at the San Francisco Chronicle in 1969 when Zodiac first...