London In 1901, London police began to dip suspects' fingers in ink and take a copy of the prints. Those inkblots made an impression around the world.
A century later, DNA analysis may be more cutting-edge, but police insist the humble fingerprint remains vital to solving crime.
"It's absolutely core to police business and it'll be some years before it dies a death," said Bruce Grant, head of Scotland Yard's Fingerprint Bureau, which last year solved 10,000 cases from marks left at crime scenes.
More than 400 delegates from 26 countries gathered Wednesday for a conference marking the centenary of the fingerprint bureau and comparing methods and technology in what one speaker called "the art and science of fingerprinting."
The bureau was the brainchild of Sir Edward Henry, a British official in India who took an interest in the nascent science of dactylography the use of fingerprints to establish identity. It's based on the observation that no two people have the same pattern of ridges on their fingertips, palms or feet.
In 1900, Henry published a book, "Classification and Uses of Fingerprints." His system grouped the ridge patterns of prints into categories: loops, arches and whorls.
On July 1, 1901, Henry, by then assistant commissioner of Scotland Yard, established the Metropolitan Police Fingerprint Bureau.
It was not the world's first that was set up in Argentina in 1892 but it was easily the most influential, spawning imitators around the English-speaking world, including a New York office that opened in 1902.
Fingerprinting was a revolutionary advance on previous, unwieldy identification methods, one of which the Bertillon system involved measuring suspects' fingers, feet and skulls with calipers.
Metropolitan Police Commissioner Sir John Stevens called the bureau's birth "a landmark for policing and criminal investigation."
Stevens lauded the bureau's achievements from 1902, when a thumb-mark on a windowsill led to the conviction of Harry Jackson for a London billiard-ball theft, through the capture of Kenneth Erskine, a serial killer dubbed the "Stockwell Strangler," in 1986.
"He never admitted his eight murders of old-age pensioners, but his palm-print on the bathroom window sealed his fate," said Stevens.
Over the last century, the Met's fingerprint bureau has processed 10 million sets of fingerprints and made 100 million comparisons leading to half a million identifications.
Fingerprinting remains a blend of the old-fashioned and the high-tech.
Experts still pore over inky smudges. But the conference also displayed computer systems that hold vast databases, software to reconstruct fuzzy prints and hand-held fingerprint scanners.
The conference, which began Tuesday and runs through Friday, was sponsored in part by the U.S. firm Cogent Systems, which makes such fingerprint technology.
"Fingerprinting is not old-fashioned," Grant said. "DNA and fingerprints complement one another. And remember that identical twins have the same DNA, but different fingerprints."
Grant points out that British police have a database of 5 million fingerprints but only 1 million DNA samples though the government hopes to increase that to 3 million within three years.
As for Sir Edward Henry, commemorated this week with a plaque on his former home, fingerprints came back to haunt him. In 1912, a man who had been denied a cab driver's license because his fingerprints were on file for being drunk and disorderly shot Henry three times. Henry survived; his assailant was sentenced to 15 years. Fingerprint evidence played no part in his conviction.