The boyfriend of Tia Sharp's grandmother is being questioned by police on suspicion of murder - as CCTV pictures showed his final minutes before his arrest.
Stuart Hazell, 37, walked into a shop in the south London borough of Merton, spoke to the shopkeeper and bought a small bottle of vodka and a cigarette lighter.
He then purchased the same items during a second visit shortly afterwards. Hazell was seen by an 11-year-old girl whose stepfather then called the police.
Hazell was detained in a public place - believed to be a park - on Friday evening, hours after officers launched a manhunt for the suspect and warned members of the public not to approach him.
The news came after investigators discovered a body at the home Hazell shares with Tia's grandmother Christine Sharp in New Addington, near Croydon, south London.
A team of forensic officers found the remains during a fourth search of the home, prompting some to ask questions about why it took so long for them to find them.
Officers did not reveal where the corpse was discovered, but officers were seen taking a ladder into the property on Friday afternoon, sparking rumours that it may have been in the loft.
The body has not yet been identified and a post-mortem examination is expected to take place in the coming days.
Tia, who was reported missing on Friday the previous week, was last seen alive at the property. Hazell said he was the last person to see her.
He was detained at 8.25pm on Friday after he was identified by a member of the public, police said.
Following his arrest he was filmed by TV news cameras being driven into Sutton police station in south London handcuffed to a police officer in the back of a car.
Commander Neil Basu said: "When police investigate cases as difficult and challenging as this, it is important that we do not just focus on one line of inquiry.
"For example we had over 60 reported sightings of Tia, 800 hours of CCTV footage to examine and 300 plus calls into the incident room. All of these lines of inquiry were in the process of being followed up."
Stressing that a number of searches took place at the address, he continued: "When Tia was first reported missing, officers searched her bedroom as is normal practice in a missing persons inquiry.
"A further search of the house took place in the early hours of Sunday morning by a specialist team. This was then followed by another search of the house by specialist dogs on Wednesday lunchtime.
"What we now need to establish is how long the body had been in the place where it was found."