Milly Dowler's uncle may have come face to face with the schoolgirl's killer hours after she was snatched off the street, the Old Bailey has been told.
Levi Bellfield returned to his home to dispose of the 13-year-old's body in the middle of the night as Brian Gilbertson searched for her by torchlight, jurors heard.
Mr Gilbertson said he saw a man of Bellfield's description with a dog walking towards a bin shed at the block of flats near where Milly was last seen and where Bellfield lived.
Brian Altman QC, prosecuting, said Mr Gilbertson was a long-lost uncle of Milly who had recently been re-acquainted with the family.
He had become concerned about his missing niece and began his own search in the early hours of the morning after she vanished in Station Avenue, Walton-on-Thames, Surrey, on Thursday March 21, 2002.
After searching the railway station with a torch, Mr Gilbertson found himself at flats in Collingwood Place, off Station Avenue, where he saw a man with a dog walking "with an air of confidence" towards him.
Mr Altman told the jury: "You can conclude that the man Mr Gilbertson saw in the early hours was the defendant who had returned with the dog. If the prosecution is right that he abducted and killed Milly Dowler, then he had to dispose of her body and clean up."
Bellfield went on to murder two students - Marsha McDonnell and Amelie Delagrange - and attempt to murder a third, Kate Sheedy, during the next two years, the court heard.
Former wheelclamper and bouncer Bellfield, 42, formerly of West Drayton, west London, denies Milly's kidnap and murder.
He also denies the attempted kidnap of 11-year-old Rachel Cowles in Shepperton, Surrey, the previous day.