The 16-year-old grammar school pupil was stabbed more than 40 times
A man whose name was written on a cardboard sign which claimed he was the killer of a Kent schoolgirl 17 years ago has been ruled out of the inquiry.
Claire Tiltman, 16, was murdered in an alleyway in Greenhithe on 18 January 1993, while on her way to see a friend.
The piece of cardboard was found next to a plaque in memory of the teenager.
Det Ch Insp Dave Withers, who has spoken to the man, said: "I'm as satisfied as I can be that he's not involved in the crime."
He said police had urged the person who wrote the card to come forward, but no-one had.
"If anyone out there has any information that could lead us to an offender then we'd be pleased to hear from that person, and they can leave us messages confidentially if necessary, but not cards at crime scenes like that was left," he said.
The cardboard sign was found on 3 February by a local reporter and claimed to name Claire's murderer, the type of car he drove and the firm he worked for.
The Dartford Grammar School for Girls pupil was stabbed more than 40 times in the alleyway off London Road as she took a shortcut to visit friends four days after her 16th birthday.
No-one has been charged with her murder.