The Essex schoolgirl has not been seen for three weeks since she left her home in East Tilbury to catch the school bus.
The detective leading the search for the 15-year-old said he now believes that Danielle has been abducted.
Police have yet to find any trace of the schoolgirl, despite extensive searches of common land near her home and repeated public appeals.
Detective Superintendent Peter Coltman, leading the hunt for Danielle, said it was "very, very unlikely" that she had run away.
He added: "I believe that she has been abducted. I don't know what happened to her after her abduction."
Mr Coltman, speaking as police divers searched a water-filled quarry about half a mile from Danielle's home, said the lack of information about the youngster was forcing officers to think the worst.
He said there was a good chance someone may have seen the teenager with her abductor at around 0800BST on 18 June.
He also urged people living in the Coronation Avenue area to think whether they might have seen Danielle as she walked towards a bus stop.
Mr Coltman said a reported sighting of a girl matching Danielle's description getting into a blue Transit type van in Coronation Avenue may not have been her.
"I would urge anyone living in the Coronation Avenue area to think whether they could have seen Danielle getting into any sort of vehicle, or with anyone on that morning of the18th.
"If they have the slightest suspicion about anything then please tell us. It might be that someone saw her but does not think it was her because they didn't see a blue van."
The focus of police activity is now on searching isolated areas around East Tilbury where a body or clothing may be hidden.
Danielle was last seen by two friends walking to catch a school bus on Monday 18 June.
Officers from Sussex police are this week expected to begin a review of the way Essex police have handled the investigation.
Emotional appeal
Police have said they are becoming increasingly concerned about Danielle's welfare.
In an emotional appeal last week, Danielle's mother Linda Jones said the family were missing her, especially her two brothers.
"You just wake up every morning and hope that it's not real. But it is."
Mrs Jones said she and her husband would not give up hope that their daughter would be found.
"We can never give up the hope that she will walk back through that door.
"You just watch the clock go around and hope that you will hear something."
Danielle is 5ft 7in, slim, with blue eyes and long blonde hair and a brace on her teeth.