The man held for the last three days in connection with the disappearance of a five year old from Wales, has been re-arrested on suspicion of murder.
Mark Bridger who was born in Sutton, is being questioned by police over the disappearance of April Jones.
The 46-year-old who is believed to have attended Shirley High School and John Ruskin in Croydon in the early 80s, was taken into custody on Tuesday afternoon.
April was abducted from near her home at around 7pm on Monday and was last seen by another child getting into a vehicle near her home.
Police teams have spent the last few days searching the River Dyfi in the Welsh town of Machynlleth.
Officers, who had been aided by members of the public, said they now only required professional searchers in the hunt.
Det Supt Reg Bevan said: "Mark Bridger has been arrested on suspicion of the murder of April Jones.
" He remains in custody in Aberystwyth and continues to be questioned.
"The arrest does not detract from our efforts to find her. Her family has been informed of this development and they continue to be supported by our specialist trained officers."
He renewed his appeal for information about Mr Bridger's movements and that of his vehicle.
"We are looking to trace the movements of Mark Bridger between 6.30pm on Monday and 3.30pm on Tuesday, and any sightings of him between these times.
"We also need information regarding the movements of the blue Land Rover Discovery registration L503 MEP between these times."
Forensic examination is taking place on the vehicle.
"While this is a significant development, I appeal for information to find April," said Det Supt Bevan.
Do you know Mr Bridger's links to Croydon and Sutton? Contact the newsdesk on 0208 722 6353 or email firstname.lastname@example.org