Moving backwards from the murders thirty-one men committed, through their adult lives, relationship histories, and their childhoods, David Adams sought to understand what motivated these men to kill. The patterns he found reveal that the murders were neither impulsive crimes of passion nor were they indiscriminate. Why Do They Kill? is the first book to profile different types of wife killers, and to examine the courtship patterns of abusive men. The author shows that wife murders are not, for the most part, "crimes of passion," but culminations of lifelong predisposing factors of the men who murder, and that many elements of their crimes are foretold by their past behavior in intimate relationships.

Key turning points of these relationships include the first emergence of the man's violence, his blaming of the victim, her attempts to resist, his escalation, her attempts to end the relationship, and his punishment for her defiance. Critical perspective on the men's accounts comes from interviews with victims of attempted homicide (standing in for the murder victims) who survived shootings, stabbings, and strangulation. These women detail their partner's escalating patterns of child abuse, sexual violence, terroristic threats, and stalking. The section on help-seeking patterns of victims helps to dispel notions of learned helplessness among victims.