A TAXI driver is being held by police on suspicion of two murders, including missing nightclubber Sian O'Callaghan.
Detectives, who have been searching near the famous White Horse chalk figure in rural Oxfordshire, England, have found Miss O'Callaghan's body and say they know the location of the second victim.
Det Supt Steve Fulcher said the 47-year-old man -- named locally as taxi driver Christopher Halliwell -- had told them the locations of both bodies.
However, mystery still surrounds the identity of the second victim as the search for missing Sian dramatically became a double murder inquiry.
The suspect's arrest came hours after police seized a green taxi which was seen early on Saturday when she disappeared after leaving a nightclub in her home town of Swindon, Wiltshire.
"The locations of two bodies have been identified to me by this individual, one of whom has yet to be identified formally, but I am quite clear is Sian," said Det Supt Fulcher.
A Toyota Avensis estate with taxi markings was seen between 3am and 4am and 12pm to 9pm on Saturday between Swindon and Savernake Forest, near Marlborough, where police have also been searching.
Police reportedly arrested the suspect outside an Asda supermarket in Swindon.
A green Toyota was also taken away on the back of a trailer.
Officers began searching a home in the town's Ashbury Avenue. A white police tent was erected in the front garden of the semi-detached house, which was cordoned off and had three police vans parked outside.
Brian Jerome (71) who lives opposite, said the house was owned by the man's partner, who had lived there a long time with her three children, all girls.
"I thought he's lived there about four or five years but my other neighbour said they thought it could have been longer," the retired toolmaker said.
"He's a really nice guy. He'd always have a smile and he'd often be out working on his car.
"I couldn't believe it when I heard. Nice man, nice family, nice girls."
Specialist dog teams have been helping the search after mobile phone technology pinpointed several areas of interest in 4,500-acre Savernake Forest.
Police revealed earlier this week that phone records put Miss O'Callaghan's mobile somewhere in the forest 34 minutes after she left Suju nightclub at 2.52am on Saturday.
It was a journey that could only have been made by car, police said.
Miss O'Callaghan, an office administrator, was caught on CCTV leaving the nightclub, in Swindon's Old Town area, after an evening out with girl friends.
She lived in a flat just half a mile away with her boyfriend Kevin Reape (25).
Miss O'Callaghan's family have thanked members of the public who have helped in the search for "our beautiful girl".
On Monday, Miss O'Callaghan's boyfriend made a tearful appeal for vital information.
Mr Reape, a quantity surveyor, was supported by his girlfriend's family, including her parents Mick (51), and Elaine, (48), brother Liam (24), and sister Lora (19).
Mr Reape, who spent the day at Cheltenham races, raised the alarm at 9.45am on Saturday after she failed to return to their flat. A stretch of road about 15 miles east of Swindon, near the village of Uffington, has been closed.
Police searched a wooded area to the side of the road which leads into a small valley.