Detectives investigating the disappearance of Tia Sharp in New Addington have stressed the investigation remains a missing persons inquiry.
The partner of Tia's grandmother returned home last night after being questioned by police as a witness in the disappearance of the missing schoolgirl .
Tia, who has never run away before, seemingly vanished without a trace on Friday afternoon after telling relatives she was going to the Whitgift Centre in Croydon.
She is thought to have been last seen at the house where her grandmother Christine Sharp, 46, lives with partner Stuart Hazell, 37, at the Lindens, New Addington, south-east London.
Mr Hazell, who is thought to be one of the last people to see Tia, was yesterday interviewed by police for more than two hours as a witness.
More than 80 officers have joined the hunt for the youngster, which has dragged into its sixth day, while members of the local community have staged their own searches in the area where she vanished.
Scotland Yard has received more than 300 calls and 60 reported sightings of Tia, including a member of the public who came forward saying they saw her leaving her grandmother's house at about noon on Friday.
Metropolitan Police area commander Neil Basu said police could not be "absolutely sure" who the last person to see Tia on the estate was.
He stressed the investigation remains a missing persons inquiry, with no suspects.
"I am looking to find Tia safe and well," he added.
Olympics resources have been redirected to the search which involves around 40 detectives and 40 specialist search officers.
Mr Basu said police have collected more than 800 hours of CCTV footage from buses and trams, and viewed more than 120 hours of the material.
He added that investigators would continue to collect CCTV as part of the "24/7 process".
Searches have covered a 500-metre radius around Tia's grandmother's house, including woodland, garages, lock-ups and a school.
Mr Basu said he did not feel the schoolgirl would have left the area and the search was focused on the neighbourhood and Croydon, where Tia was heading to.
He thanked people from the Croydon and Mitcham areas, and praised those involved in the search for their "generosity, their energy and their commitment".
The local community has rallied to help search for the missing 12-year-old, donning Find Tia T-shirts and handing out leaflets to passing motorists.
Candles and tealights have been left at a makeshift vigil at a bus stop near Tia's grandmother's house - which was yesterday searched by police dogs - along with hand-written messages asking for the schoolgirl to be brought home.
The Sun newspaper has offered a £25,000 reward for information that will lead to police finding Tia.
Phillip Wheatley, her headteacher at Raynes Park High School in Merton, described her as friendly young person who is well liked by staff and students and enjoyed a successful first year at the school.
He said: "Our thoughts are with Tia and her family at this time.
"I would urge anyone who thinks they may have seen Tia, or who has any information on Tia's whereabouts, to contact the police immediately."