Milly snatched in 'chance abduction'

The CCTV footage has been studied extensively

Missing teenager Amanda Dowler was snatched in a "chance abduction", police have revealed.

Officers say her kidnapper carried out the assault in a 60-second "window", probably by trickery.

They put forward the theory on Friday, as they released new closed circuit television footage.

An eyewitness saw the schoolgirl - known as Milly - walking along a road in Walton-on-Thames, Surrey, as she headed home from school.

Milly went missing on 21 March

But CCTV footage shot from a building further along the road failed to capture her image.

The BBC's Clarence Mitchell says Surrey Police now believe she was snatched in the "gap" between the point where she was sighted and the building where the camera was positioned.

Police are now trying to identify a number of people shown on the footage, to see if they remember seeing Milly walking towards them.

They are particularly hoping to trace a man with a guitar, a blonde female, a group of women and a cyclist.

It is most unusual not to have any witness, body, scene or main suspect

Detective Chief Superintendent Craig Denholm

Officers say the footage is a "key piece of evidence", but that the quality is variable, particularly where the camera is looking into the sun.

They have sent the video to the FBI in an attempt to get clearer images.

But Detective Chief Superintendent Craig Denholm, of Surrey Police, said he was "not optimistic" the extra forensic analysis would make the pictures any clearer, because British experts had already tried.

The teenager, whose 14th birthday was last month, disappeared in March after getting off a train a station early at Walton-on-Thames to visit a cafe with friends.

'Extremely challenging'

She phoned her father to say she would be home in half an hour, and was last seen walking home along Station Avenue.

Officers said on Friday that CCTV cameras at the station were not working on the day she went missing - they were in the process of being mended.

Milly's parents have endured an agonising wait for news

Milly's disappearance sparked a UK-wide police investigation, which has received much coverage in the media.

Mr Denholm said the investigation was "unique and extremely challenging".

"It is most unusual not to have any witness, body, scene or main suspect," he said.

A total of 140 items had been removed from the Dowler home, and there had been 30 searches underwater - with extensive investigations in the nearby rivers and lakes.

Last month, Milly's parents Bob and Sally were told by officers their daughter was probably dead.

A police spokeswoman said the couple had been told to "expect the worst".

Vehicle sightings

Officers hunting for the teenager also rejected reports they had made a number of mistakes, including the allegation they had failed to treat her disappearance from the outset as a potential murder inquiry.

Surrey Police said the force had always treated the case as a "serious and critical incident".

So far officers have arrested two men. One has been eliminated from the inquiry, but investigations are continuing with the second.

Officers looking into possible sightings have now eliminated a blue Saab from their inquiries, but are still interested in tracing a red car.

Mr Denholm said they were also still interested in white vans seen in the area, but it was a difficult line of inquiry as that type of vehicle was so numerous.