In 1903 an African American man named Will West was convicted for a minor crime in northwest Kansas.
According to The Vintage News, when West was processed through Leavenworth Penitentiary, authorities made a startling discovery – he was already serving a life sentence in that same prison for first degree murder.
At the prison West was processed through the Bertillon identification system and his face matched with William West who was already serving time in the prison.
The Bertillon identification system was invented by the French handwriting expert, dedicated criminologist, and biometrics researcher Alphonse Bertillon, and implemented in American prisons from 1887 so they could keep detailed report cards on inmates.
Basically they took a mug shot of the inmate and then wrote up a detailed description of the inmate's facial features. These two things - along with their name - were kept in the prisoner's file.
This system worked really well until Leavenworth Penitentiary discovered they had two Wests - one called Will and one called William - and they had almost identical facial features.
That's when authorities realised they needed a better way to identify and distinguish between inmates.