Police hunting Jessica Chapman and Holly Wells were tonight waiting to see if a kidnapper would meet the midnight deadline set by police to phone a special hotline number.
So far no one has responded to a dramatic "call me" plea by Detective Superintendent David Beck who said in a TV appeal that he had sent messages with details of the hotline to Jessica's blue Nokia mobile phone, not seen since the best friends vanished.
As the clock ticked towards the deadline, police did not say what would happen if the abductor had not called.
Detective Chief Inspector Andy Hebb said "many, many positive lines of inquiry" were still being actively pursued and the personal appeal to any abductor was only one of them.
He refused to elaborate for "operational reasons" but emphasised that the investigation - one of the biggest of its kind ever mounted in the UK - was "most certainly not back to square one".
Police still believe the girls are alive, he said.
As the parents of the Cambridgeshire 10-year-olds waited anxiously for news, they made another emotional appeal through police for the safe return of their daughters.
Mr Hebb said: "Holly and Jessica, your parents still love you. They want you back safe and well."
With no sign of any breakthrough, Cambridgeshire police disclosed details of a shake-up at the top of the inquiry team although they denied the change was in response to criticism over their handling of the inquiry, and insisted it was for practical reasons given the mushrooming size of the operation.
Earlier today, search teams widened their operations around the town of Soham, while officers extended house-to-house inquiries.
The inquiry team - now 426 strong - is sifting through 14,000 items of information received since Holly and Jessica went missing. They have followed many dud leads, including excavating two apparent graves in woodland near Newmarket, only to decide later they were badger sets.
Detectives have discounted a potential sighting of the girls in a green car after taxi driver Ian Webster admitted his dashboard clock was an hour fast.
Meanwhile, police confirmed they had received a report from a Soham builder, David Kitching, who saw a man and women in a green car staring "intently" at children in a restaurant on the night the girls went missing. But detectives said the information was not being viewed as particularly significant.
PA