Even if you’ve never been hauled downtown in a paddy wagon, there’s a chance you’ve had your fingerprints taken. They’ve been used to establish people’s identities for thousands of years, but it wasn’t until the early 20th century that police used them to track criminals. 

Before that, the Bertillon system was the standard identification method in much of Europe and the U.S. It measured more than a dozen different body parts — including the ears, nose, arms, head circumference, sitting height, and standing height — to identify suspects and criminals. Eye color, scars, and other distinguishing features were noted on a standardized card that also included a mug shot.

The system was named for its creator, French anthropologist Alphonse Bertillon, who developed it in 1879. By 1898, 10 American cities including New York, Philadelphia, and Boston had begun using the system and coordinating with one another. But its flaws soon came into focus during the Will West case. Two men, named Will West and William West, who looked nearly identical and whose Bertillon measurements were likewise indistinguishable, ended up in the same prison, and it wasn’t until their fingerprints were compared that Will was able to prove his (relative) innocence. The case marked a turning point in police methodology, with fingerprinting emerging as the standard form of identification.