By Matt Maclean BBC News Online, in Soham

Despite the efforts of hundreds of officers working on the case, police are still no closer to knowing what has happened to Holly Wells and Jessica Chapman.

But while few firm details are known, detectives are starting to build up a picture of the girls' movements on Sunday evening, the time they went missing.

Holly and Jessica spent the afternoon playing together before heading to Holly's home in Red House Gardens for a family barbeque.

A friend of Jessica's told police she had seen and spoken to her just before that, by a chip shop in the High Street at around 1700 BST.

Searchers continue to look for clues

Holly's home is just a few minutes walk from the town centre and a picture of both girls in their Manchester United tops was taken at the Wells' residence shortly after they arrived.

A clock visible in the photograph read 1704, although police are trying to determine if it was set accurately.

From 1711 to 1735, the computer at Holly's house was in use, leading police to believe the girls were still there, but sometime after that they went out.

The next confirmed sighting was at 1817, when CCTV cameras at the Ross Peers sports centre - on a nearby college campus - showed the girls crossing the centre's car park.

But they may have returned to the main road, Sand Street, to get there as they were seen entering the car park from that direction via an alleyway, Gidney Lane.

	:	Holly and Jessica
Maps showing focus of the investigation

Two girls wearing red tops were seen walking along the main road between school and the town centre at 1815, though police are not treating this as a confirmed sighting.

They are more confident over four separate sightings of the pair walking along Sand Street towards the town centre, but accept that the time given by the witnesses - approximately 1830 - may not be accurate.

Staff at the sports centre say the girls came in at around the same time to buy sweets from a vending machine in the entrance lobby, although again these reports are yet to be confirmed.

War memorial

Centre staff believe the girls left the college grounds via College Way, and the next confirmed sighting took place at 1845 in the town centre nearby.

Again, four separate witnesses saw the pair in the vicinity of the town's war memorial, in Red Lion square, by the High Street.

One more witness has reported seeing two girls fitting the description of Holly and Jessica at the southern end of Soham - a considerable distance from the town centre.

The girls were reportedly seen at 1900 on the A142, near the Q8 garage, at the Downfield Roundabout, walking south in the direction of Newmarket, but officers stress this report is also unconfirmed at this stage.