LONDON >> On a sticky August afternoon in 2011, as rioters looted and burned in the streets outside, a small number of police officers gathered in a room in North London.

Projected on the wall was the blurry silhouette of a man with a black woolen hat pulled deep over his forehead and a red bandanna covering all but his eyes. Security cameras across the city had tracked the man setting fire to cars, stealing from shops, beating up passers-by, even hurling gasoline bombs.

But he was always masked.

"We need to identify this fellow," the sergeant said. "He’s one of the worst."

At that moment, Gary Collins, a constable from the local gang unit, walked in. He took one look and said, "That’s Stephen Prince."

Friends call Collins "Rain Man" or "Yoda" or simply "The Oracle." But at Scotland Yard, London’s metropolitan police force, he is known as a "super recognizer." He has a special gift of facial recall powers that enables him to match even low-quality and partial imagery to a face he has seen before, on the street or in a database and possibly years earlier. The last time he had come face-to-face with Prince was during a fleeting encounter in 2005.

Soft-spoken and gentle-mannered, Collins carries a baton and pepper spray, but no gun. His weapon is his memory: Facial recognition software managed to identify one suspect of the 4,000 captured by security cameras during the London riots. Collins identified 180.

"Computers are no match for the super recognizers," said Detective Chief Inspector Mick Neville, head of the Central Forensic Image Team at Scotland Yard and mastermind of the squad.

With its estimated 1 million security cameras, London is pioneering a whole new area of detection, one that could be cheaper than DNA analysis and fingerprinting and relies above all on human superpowers. Scotland Yard’s ever-expanding team of 152 super recognizers is made up of men and women from across the force who score at the top end of a facial recognition test originally devised at Harvard in 2009. Collins, the star of the unit, is in the rarefied 1 percent range.

Traffic police and jailers, those patrolling neighborhoods and officers who specialize in violent crime, the super recognizers have more than tripled the number of identifications since April 2013. They are deployed to pick out known thieves and sexual offenders in crowds of tens of thousands at rock concerts and to round up pickpockets at tourist spots like Buckingham Palace and Oxford Circus. This year, they solved the high-profile murder of a teenage girl that had led to the mobilization 600 police officers across eight forces, the biggest search operation since the 2005 London bombings.

The term was coined in 2009 by Richard Russell, a postdoctoral researcher at Harvard. He was studying prosopagnosics, or those with face blindness, and found that about 2 percent of people had a very poor ability to recognize faces. Then he grew curious: Were there people at the other extreme, with extraordinary facial recall?

Russell, now an associate professor of psychology at Gettysburg College, tested four individuals who believed they had superior face-recognition ability. The tests included the Cambridge Face Memory Test, using images with no hair or other identity clues, and a Before They Were Famous Test, in which participants have to identify celebrities from photographs taken mostly when they were children. All four participants scored far above the controls. Since then, larger-scale tests predict that 1 or 2 percent of people are super recognizers.

Around the same time in London, Neville was fighting a lonely battle with his superiors to put in place a system for circulating images of suspects caught on security cameras. "We had all the evidence, but we weren’t using it," he said in a recent interview. "The idea was that the cameras themselves would deter the bad guys. They didn’t."

Skeptics complained that he wanted to pay officers "to watch television." Privacy advocates warned of intrusiveness and misidentifications. Even psychologists were doubtful. When Neville asked Josh Davis of Greenwich University in April 2011 to test some of his best officers, Davis did not expect to find much.

But the test, of an initial 20 police officers with above average identification records, surprised both men: Most of the officers scored well above average and a handful, including Collins, were off the charts.

When rioting broke out in August that same year and 200,000 hours of camera views with thousands of images of suspects flooded in, these early super recognizers got their first assignment. They identified 609 suspects, 2 in 3 of whom went to court. Ninety percent of those charged were convicted. Prince, the masked man picked out by Collins, got six years, one of the longest sentences of all.

Evolutionary psychologists are intrigued by super recognizers. Their facial recall is rarely matched by photographic memory in other parts of their lives. Collins, 48, who studied design before he became a police officer, has identified more than 800 suspects but cannot remember a shopping list. "I have to write that down," he said.

An unassuming man with cropped graying hair and a soft Cockney lilt, Collins patrols the same streets in North London he grew up in. He has become famous among colleagues and villains alike. The officer sitting opposite him in their gloomy ground-floor office likens his mind to a Rolodex: "You show him a photo, 30 seconds later the name pops up. And he’s always on the mark."

Once, in the police van after a raid, a gang leader who had been arrested asked: "Who ID’d me? Who is this Gary Collins?" When Collins put up his hand, he said, "Man, everyone in prison is talking about you." They still see each other on the street now and again.

"He’ll test me on his gang mates: ‘What’s his name?’ he’ll ask," Collins said. "When I tell them they cheer and give me a high five."!~neIP~!

As a child, Collins was oblivious to his talent. "I always recognized people, but as a kid you don’t know you have a gift, you just think everybody is like you."

The son of a telephone engineer and a veterinary receptionist, he would beat his family and friends at ordering the colors on a Rubik’s Cube. He was bad in school but good at art, with a particular aptitude for drawing portraits. Before exams, he would fill a little book with colorful diagrams and mnemonics.

"They called me ‘The Book,’" he said.

But it was only when he joined the police in 1995 that he became aware of his gift. The new boy on the beat in Greenwich, in London’s southeast, he would spend hours looking at the worn Polaroid prints of neighborhood villains on the wall. "I was drawn to those pictures," he said. "I used to look at them all the time."

Then, out on patrol for the first time with a senior officer, he would reel off the names of the people they came across. "How the hell would you know, new boy?" his partner asked him.

Off duty, super recognition can be a curse. Recently, Collins almost got punched. "I think sometimes I stare a bit too long, but I can’t help it," he said. "This guy I was looking at was like: ‘What are you looking at? What are you looking at?’ "

He deliberately lives outside London to avoid running into wanted faces from his beat. (Recently, he had to cut short an outing to the mall with his sons when he recognized a gaggle of gang members while buying sneakers.)

He reckons that his oldest son, 11 years old and soccer-obsessed, could be a super recognizer. "He knows football players in countries and teams I haven’t even heard of," Collins said. "Who knows? He might have the gift."

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