A true crime story set in 1890's France, The Killer of Little Shepherds weaves together the story of a serial killer and the developing forensic sciences that eventually help catch him. When Joseph Vacher is rejected by his true love, he snaps and decides that if he can't have her no one will. That is the first in a long line of killings. Vacher is released from an asylum only a year after this first murder and begins wandering the countrysides of France, killing young teens along the way. On his trail is the head of legal medicine, Alexandre Lacassagne, whose breakthroughs in profiling bring about the capture of Vacher.
The last section of the book is Vacher's trial, which goes into great debate over the plea of criminal insanity, when a person should be held responsible for their actions and nature versus nurture.
I've read several books with similar themes and find it fascinating how doctors and psychologists (alienists) seemed to recognize that each person is unique and to understand there must be a way to identify and single out a person. This revelation appears to have occurred nearly simultaneously in the USA, England, France and other developed nations, and their discovery process was very similar. I am intrigued by the emerging information in medicine and forensics that have led us to where we are today. Makes me wonder where we'll be in another hundred years!