The girl, from Raincy in the eastern suburbs of Paris, was with her friend when she saw a man who had attacked her just two days before.
"It was about 1.30pm," the girl told newspaper Aujourd'hui. "I was waiting for the bus just between Raincy and Clichy-sous-Bois when a man driving a Peugeot 106 asked me for directions to the train station."
"He pretended that he couldn't hear me and opened his door, then grabbed me by the wrist and pulled me into the car. After pulling over in an alleyway he pressed up against me and put his hands in my bra. I screamed and ran away from the car."
Two days later, she was with a friend when she saw the man again, sitting in a restaurant.
"He was having lunch," she said. "When he saw me he started panicking. My friend took a picture of him with her mobile phone and when he left the restaurant we followed him discreetly to his car and took down the registration details."
Thanks to their undercover work, the 49-year-old man was later arrested by police and handed over to prosecutors.