A team of British 'super recogniser' officers is helping German police identify suspects after hundreds of sex assaults were reported in Cologne on New Year's Eve.
Scotland Yard's specialist unit is made up of officers with a natural ability to recognise faces. They are using CCTV footage to track down suspects.
Almost 60 people have been arrested in connection with - the over 500 - attacks in the city last December.
Detective Chief Inspector Mick Neville is head of the unit: "They are already linking suspects together, either their associates, or finding these sames suspects in several pieces of footage."
The compliment is that the Germans have asked to keep them."
Often the investigators need only a fleeting glimpse of a suspect to link a series of crimes committed by the same offender.
Super recognisers
Detective Chief Inspector Neville, says: "We've found that certain officers were just very good at looking at faces, or bits of faces, an ear or a nose, a suspect's gait, and recognising the same characteristics in other footage of unsolved crimes.
"What it means is that instead of a criminal getting charged for one offence from one bit of CCTV evidence, we can link their crimes and charge them with 10, 20, 30 or even 40 crimes.
"That means they are more likely to plead guilty and more likely to go to prison."
Past successes
The squad was created after success in identifying many suspects during the London riots in 2011.
In 2014 it helped track the last-known movements of schoolgirl murder victim Alice Gross in West London.