The policeman leading the hunt for the killer of Amanda Dowler says searches at the woodland where her body was found could last for weeks.

Detective Chief Superintendent Craig Denholm also said footage from CCTV cameras on the M3 motorway near the scene is to be studied for clues.

More than 100 hundred officers from the Hampshire and Surrey police forces are involved in the investigation, with many sited at Yateley Heath forest near Fleet where the body was found.

Amanda, known as Milly, disappeared from her hometown of Walton-on-Thames on 21 March and her remains were discovered last Wednesday.

One of the last family pictures of Milly (centre)

Mr Denholm said: "The search is a painstaking process.

"The vital clue could well be in this area and we are determined to be as thorough as possible to find that lead.

"I anticipate this search to continue for some time, potentially going into days, possibly weeks.

"We now have six victim recovery dogs from the Metropolitan police assisting in the search.

"Once the dog search has been completed trained officers will conduct a fingertip search of the area.

"This involves a line of officers, shoulder to shoulder on their hands and knees, fingertip searching for evidence."

Expert help

So far, none of Milly's possessions, nor her clothes, have been found.

Police are also waiting for DNA evidence to show conclusively that the body is Milly, although dental checks on the remains matched the 13-year-old.

Officers have conducted house-to-house enquiries in the area surrounding the forest and have asked for anyone who may have visited the area from 21 March onwards to get in touch with them.

Milly's body was found in Yateley Heath Forest

So far, there have been 400 calls from members of the public since the body was discovered.

Officers from the enquiry are locating CCTV footage from motorway cameras between Walton and Yateley Heath forest that might assist the investigation.

A statement from Surrey police said: "It will take time to establish exactly what has happened to Milly and it is much too early to start speculating."

To help in the search, police have called in a forensic ondontologist, a forensic archaeologist and a vegetation and soil expert.