The two parts of the title indicate the two approaches that Richard Rhodes takes in the book. It is both an exploration of the reasons that human beings kill and a professional biographical treatment of Lonnie Athens, the “maverick criminologist” of the subtitle. Rhodes notes at the outset that his original intention was to write a book about human violence and, especially, murder. Once he realized that Athens was a major figure doing this type of analysis, he became more interested in the field itself and the ways this investigator had shaped it.

One reason for Rhodes’s interest in Athens was that both men had been drawn to studying violence in part because of boyhood experiences in which they endured abuse by adults. The childrens' sense of powerlessness had motivated desire for a different kind of power when they grew up; the quest for intellectual and emotional understanding would support the rejection of violence in their adult behavior.

Rhodes presents findings from different disciplines and interdisciplinary fields, including psychology and criminology, that delve into historical and recent cases of homicide and other extreme violent behavior. The book is heavily dependent (some would say, too dependent) on Athens’s pioneering books, especially The Creation of Dangerous Violent Criminals (1992). Because Rhodes’s research led him to understand that Athens’s work was not initially well understood, he also spends much of the book detailing how Athens entered the criminology field, in what ways his approach differed from traditional approaches, and how his work influenced subsequent generations and current practices.

Athens conducted in-depth interviews of hundreds of incarcerated men as the basis for his conclusions. This was a sharp departure from much of the previous, heavily quantitative research. From broad, demographic characteristics such as age, area of residence, and race, researchers determined general patterns. In addition, mental illness or the “hard wiring” of brain chemistry was also favored as an explanation of individual pathology. Athens was able to see more-fine grained similarities within smaller groups. Both Athens and Rhodes remain optimistic that this type of research can support policies that will help prevent people from turning into killers.