Independence Day weekend, 1960: a young cop is murdered, shocking his close-knit community in Stamford, Connecticut. The killer remains at large, his identity still unknown. But on a beach not far away, a young Army doctor, on vacation from his post at a research lab in a maximum-security prison, faces a chilling realization. He knows who the shooter is. In fact, the man—a prisoner out on parole—had called him only days before. By helping his former charge and trainee, the doctor, a believer in second chances, may have inadvertently helped set the murder into motion. And with that one phone call, may have sealed a policeman's fate.

Alvin Tarlov, David Troy, and Joseph DeSalvo were all born of the Great Depression, all with grandparents who'd left different homelands for the same American Dream. How did one become a doctor, one a cop, and one a convict? In Genealogy of a Murder, journalist Lisa Belkin traces the paths of each of these three men—one of them her stepfather. Her canvas is large, spanning the first half of the twentieth century: immigration, the struggles of the working class, prison reform, medical experiments, politics and war, the nature/nurture debate, epigenetics, the infamous Leopold and Loeb case, and the history of motorcycle racing. It is also intimate: a look into the workings of the mind and heart.