Alphonse Bertillon was born in Paris in 1853 into a family of noted statisticians and seemed determined to disappoint them. He was expelled from school, drifted through menial jobs and a stint in the army, and in 1879 took a clerk’s post copying files at the Paris Prefecture of Police that his father arranged. The records around him were useless. Repeat offenders gave false names and nothing tied a man in custody to an earlier file. Bertillon’s answer was to measure them, reasoning that a criminal could lie about his name but not about his skeleton.

This episode follows his system of anthropometry from the jeers of inmates at La Sante prison to adoption across Europe and North America, along with the standardized front and profile photograph that survives as the mugshot. It also follows the certainty that ruined him. Called as a handwriting expert against Alfred Dreyfus in 1894 and again in 1899, with no training in the field, he offered a theory dressed in probability that helped send an innocent man to Devil’s Island.

• His first five measurements were the length and breadth of the head, the middle finger, the left foot, and the forearm.
• He preserved footprints by electroplating plaster casts in copper and used a dynamometer to record the force a burglar applied to a door or window.
• In 1912 he set a standard of 16 ridge characteristics for matching latent fingerprints, helping write the rules for the method that replaced his own.
• In Minneapolis, Black women targeted by police with his system defeated it by rotating aliases, most often the name Mamie.
• He argued Dreyfus had forged his own handwriting to make it look like a forgery. In 1904 Henri Poincare and two fellow mathematicians found the analysis without scientific value, and Dreyfus was exonerated in 1906.