First of all, this book has a bit of a misleading subtitle. It purports to be “A True Crime Story and the Birth of Forensic Science” but it’s really more about forensic psychology. As if becoming a common pattern among historical true crime books, the author follows two threads, one about a criminal and the other about an investigator, until the two converge. Now, the investigator here is Alexandre Lacassagne, who is considered one of the founders of modern forensic science, but the trial detailed in the book, that of French serial killer Joseph Vacher, was not really about forensic science, nor was forensics used to convict him (he confessed, but pled insanity).
The advent of modern forensic techniques, many of which were developed by Lacassagne, did help to corner Vacher and capture him, but most of the work was done by a magistrate named Fouquet, and he tracked Vacher the old-fashioned way. The connection between this case and forensic science is pretty thin, although much is made of the difficulties of rural autopsies in late 19th century France and how Lacassagne worked to standardize the practice of medico-legal investigation and developed techniques that are still used.
None of which really impacted Vacher’s capture and trial. In fact, most of that boiled down to the then-heated (and still murky) debate about what constitutes criminal insanity, how you know someone has it, and the ethics involved in trying and executing someone who may or may not have a mental illness that excuses him from culpability.
Vacher’s crimes were indeed horrendous. Starr’s descriptions of Vacher’s vagabond life in the French countryside is vivid and interesting, as is the historical information about the development of the scientific side of things in urban centers, but the connective tissue here is pretty thin. The writing is serviceable, although some maps and illustrations would have added much to the text.