The partly-clothed body of Janet Swanson was found by walkers in woodland behind a B&Q do-it-yourself store close to a McDonald's restaurant in Killingbeck, Leeds, West Yorkshire. Detectives believe she was killed between 4.20pm and 7.30pm on Saturday when the retail park would have been filled with shoppers.
Janet had been visiting a friend in the area three weeks after having been put into care following domestic problems with her parents..
Detective Superindent Malcolm Mawson, the officer leading the murder inquiry, said her parents, Hazel and Andrew Swanson, both 33, were devastated by the killing. He added: "It was an unnecessary killing and, as always, a tragedy because of the loss of a young life."
Janet was described as a "quiet, likeable and attractive young girl" who attended Elmet Wood School in Roundhay, Leeds.
Last night, a spokesman for West Yorkshire Police said a 15-year-old youth was helping them with their inquiries, but charges were not imminent.
Teenage girls who shared a children's home with Janet were described as "heartbroken" over her death.
Mike Evans, assistant director of social services for Leeds City Council, said: "It is an awful tragedy and everyone is absolutely devastated. The other girls are heartbroken."