By Georgina Pattinson BBC News Online

The inquiry into the murder of Danielle Jones was the largest operation Essex Police has ever undertaken and involved 944 officers.

It began on 21 June 2001 when Detective Superintendent Peter Coltman was called in to look into the disappearance of a 15-year-old girl.

She had been missing since 18 June and concerns for her safety were growing.

Before long, Mr Coltman had to take the decision to call the hunt for Danielle a murder inquiry.

Essex police scoured the county for clues

"It was an assumption and could not be allowed to foreclose other investigative possibilities," he said.

"More importantly; it was devastating news for Linda and Tony Jones.

"As with so many other things, the Joneses accepted this most difficult and heart-breaking revelation with the fortitude and dignity that they have displayed throughout the last year."

The search operation for Danielle's body began and Mr Coltman said it was far bigger than anything Essex Police had undertaken before.

Searching also produced many false dawns, where officers located recent ground disturbance or something else that indicated that a body might have been disposed of.

Among the sites searched was a building site and a derelict chemical works, farmland, fenland and mud flats.

Bone fragments

The building site, in Grays, Essex, is four miles from East Tilbury, where the 15-year-old was last seen.

The one-acre site, Connaught Place, contained a mixture of new and partially-built homes.

Initial inquiries were focused on a mound of earth that had been excavated, the newly-laid foundations of one house and the foundations and first floor of another house.

Danielle's parents are desperate to find her body

Soil samples and small fragments of bone and clothing were sent for analysis.

Police felt it was a significant site at the time but no conclusive evidence was found.

Other searches included a derelict chemical works. A site was identified in the flooded basement of a pump room, using hi-tech underwater video technology.

Specialist divers were called in and the search took five days under dangerous conditions.

Nothing, however, was found.

'Compelling evidence'

Search advisers were called in from Sussex, Bedfordshire, Thames Valley, Norfolk, London and Hertfordshire.

On some days, more than 100 officers were actively searching for Danielle.

Police will re-open the search if new leads come to light

The Essex Police helicopter was put into use covering areas such as the River Thames mud flats at low tide.

In total, since June 2001, more than 1,500 search sites have been identified and investigated for Danielle's remains. But her body has still not been found.

Campbell was arrested on 17 August on the suspicion of the murder of his niece.

Mr Coltman said: "Our evidence was circumstantial but, for the investigating team, compelling."

He explained how officers had discovered Campbell had a fascination for young girls and had developed an inappropriate relationship with Danielle.

"Perhaps most damning is Campbell's assertion that Danielle, having run away from home, chose him of all people to text to say firstly she was in so much trouble then, on 19 June, to thank him for everything."