How can Shannon just have vanished in the land of CCTV?

Search by 250 officers and untold numbers of volunteers fails to yield a single clue

Last night, in the town being combed day and night for missing nine-year-old Shannon Matthews, they were beginning to ask the question to which there is no comfortable answer: how come, in the most electronically scrutinised nation on earth and with a quarry wearing such distinctive clothing, there has been not a single CCTV image or sighting of her since she left her Dewsbury school on Tuesday afternoon?

It was a question police divers must have been asking themselves yesterday as they searched, for the second time, the Millbrook pond near Shannon's home. It was a question football fans were asking as they were handed a leaflet appealing for information – any information – about the missing girl. And it was a question being asked in the streets around Shannon's home in Moorside Road, where the bedroom curtains were drawn yesterday by police as their examination of the house and its contents continued.

And no one is probably asking this more insistently than Karen Matthews, Shannon's mother, who has now left the family home, with its broken toys in the garden and heartbreaking associations wherever she looks, to stay with friends. Where can her daughter have gone? And why has no one seen the girl with the freckly face since she stepped through the doors of West Moor Junior School at 3.10pm wearing her black coat with its fur-lined hood, and her vividly conspicuous pink Bratz boots?

For since then the massive search of this West Yorkshire town has failed to yield a single clue to where Shannon can be. More than 250 police officers, plus volunteers, have spent four days and five nights in freezing temperatures searching the alleys, streets, wastelands and moors. Shannon's face is on front pages, websites, posters, even T-shirts, and on television. But nothing.

What has emerged is that Shannon's fractured family is one of the main areas of investigation by the team of detectives trying to find her. Her mother Karen, 32, has seven children with five different fathers, but insists that her current partner, Craig Meehan, 22, has a good relationship with Shannon. But police admit the family's response to the inquiry has been inconsistent, and this has not helped them establish a clear idea of what could have been going on in her mind on the day she disappeared.

"We have been interviewing and re-interviewing family and friends trying to get a clear picture of what has gone on," said Detective Superintendent Andy Brennan, who is leading the investigation.

One of the lines of inquiry has naturally centred on the widespread reports of the messages that Shannon scrawled on her bedroom wall, which spoke of her wish to be with her father, Leon, who lives seven miles away in Huddersfield. A row of dolls on her bedroom window ledge are almost a cliché of a pre-teen girl's bedroom, but the walls of this room are not.

These were a sort of diary, and are covered with scribbles as high as she could reach. The messages include one where she expressed a desire to live with her natural father. "There is writing and scribbling all over the walls in Shannon's bedroom," Det Supt Brennan said. "There is nothing that immediately jumps out at you as being significant although there are references to her dad."

But there is no evidence that Shannon has made the journey from Dewsbury to Huddersfield. She has not been seen boarding a train or bus, nor has she made any contact since she said goodbye to her friends at the gates of her school. Police believe she would not have been carrying much money, and her mobile phone was left at home.

The search for Shannon began in earnest on the night of the lunar eclipse last Wednesday, when, with the darkening moon rising over the moors, hundreds of local volunteers joined police and mountain rescue teams on the hunt. As Karen Matthews made another, increasingly desperate plea for the return of her "princess", the Holme Valley Mountain Rescue searched the nearby Dewsbury Moor crematorium and cemetery. Divers broke the ice on frozen ponds; mounted police patrolled the town in a posse and a search helicopter circled overhead.

Police have received more than 300 calls to the incident room and have visited 200 homes around the Dewsbury area. Yesterday, police divers searched the tiny, rubbish-filled pond near Shannon's home for the second time, carrying out another painstaking search. They dredged up children's bicycles and rags – but no clues.

Chief Superintendent Barry South said the second search of the shallow pond was not based on any specific intelligence. "We are carrying out a staged phase process of searches," he said. "We have recovered at least 250 items, but none of them is linked to Shannon. We are now gravely concerned."