Detectives said they are hoping a DNA profile of nine-year-old Shannon Matthews will help them pinpoint any locations the missing nine-year-old may have visited.
Senior officers leading the massive hunt said the profile, together with a full set of fingerprints, has been pieced together by analysing items from the youngster's bedroom and other objects, including her schoolbooks.
Detective Superintendent Andy Brennan said: "Both of these items will assist the investigation in the long term."
Mr Brennan was speaking almost exactly two weeks after the last confirmed sighting of the "timid" little girl.
She was last seen leaving her school in Dewsbury Moor, West Yorkshire, on February 19, following a class swimming trip.
The detective revealed some of the painstaking work involved in the inquiry which has included 500 homes being searched on the route Shannon should have taken to her home in Moorside Road.
These searches have involved special dogs trained to spot signs of human bodies.
The detective said around 3,000 premises had now been searched in the Dewsbury area and a dedicated team was continuing to trawl through CCTV footage seized from across the town.
The senior officer said a "massive amount of resources" remained committed to the search, including 250 uniformed officers and 60 detectives.
He said this represented about 10% of West Yorkshire Police's operational strength.
