A suspected jewellery thief left his phone with a screensaver picture of himself at the scene of a crime, police said.
French national Germain Ibrahim Fofana, 27, is being sought by officers after he allegedly left his mobile behind when fleeing a branch of Ernest Jones in Kingston, south west London, "in a hurry" with £18,000 worth of jewellery.
The phone lit up after receiving a text message and he was identified as the person in the screen saver picture, the Metropolitan Police said.
Fofana is alleged to have posed as a customer interested in buying engagement rings for a female accomplice after the pair entered the shop with a child in a buggy on Sunday.
The couple then left the shop, saying they were going to see jewellery elsewhere and would return later. But Fofana returned alone after about half an hour and asked to see two rings again as well as a wedding band, police said.
He is alleged to have run out of the shop with the two engagement rings and the wedding band, leaving behind the phone in a bag.
Detective Sergeant Damion Cummings, from Kingston CID, said: "Having conducted further inquiries, the suspect has been identified as Germain Ibrahim Fofana, a 27-year-old French national.
Fofana is described as about 5ft 7in and of slim build and with short black hair. He speaks with a French accent. He was last seen wearing a light blue shirt, grey suit trousers and boating shoes.
His female accomplice is of large build, had long black hair, and was wearing all black clothing.