The bones discovered on the A23 this week are believed to include a human jawbone, The Argus has learned.
Several small bones were also found with the larger bone. Sussex Police believe they may have to use DNA technology to work out who they belonged to.
It is thought the remains may belong to the same man whose headless and handless body was found just two miles away 20 years ago, and who has become known as the Bolney Torso.
The cordoned-off scene is also in one of the areas shortlisted by detectives as a possible resting place for Gary Hampson. The father, from Brighton, is believed to have been murdered last year, but his body has never been found.
Sussex Police maintained yesterday they were keeping an “open mind” about the bones. They said nothing else had been found.
A spokesman said: “We have not yet formed a view on how the bones came to be there, or their age.
“Although very close to the carriageway it is possible that they may have been carried there by animals.
“There is no evidence to show that they had been buried, as they appeared on the surface during the process of digging and ground clearance.”
The force called in forensic archaeologists to help investigate the find, which was made as workmen cleared a wooded area for the widening of the road.
As well as murder, possible explanations being considered include suicide and natural death.
The first discovery was made at 10.20am on Monday, 100 metres south of the Slaugham turn-off on the southbound carriageway of the road, near to where a bridge carries Brighton-bound traffic over Staplefield Road.
One possibility being considered is that the bones are those of someone who was hit by a car on the A23 and knocked into the undergrowth.
Last year police staged a series of searches in the area looking for Mr Hampson, without success.
They said no evidence had been found of any link between his case and the current find.
The bones were yesterday being removed for further analysis. At 3pm yesterday a line of seven police officers were on their hands and knees combing the area.
They were seen bagging items as the Sussex Police helicopter circled overhead.
Earlier, more than 20 officers had been involved in searches at the scene. Some had hedge-cutting equipment to clear the undergrowth.
Helen Baker, who keeps her horses in the next field along, said: “A workman came over on Monday and said, ‘I’ve got some gossip for you – the ecologists have found a human jaw.’ “The police haven’t said much more.”
Nicholas Soames, the Conservative MP for Mid Sussex, lives only half a mile away in Slaugham, a hamlet with only 24 houses, a church and a pub.
Peter Sadler, who lives 100 metres from the site, said police had told him the find was not “fresh”.
He added: “Before November that area was covered with trees – you couldn’t see the road. Now that’s all gone.
“It’s a spooky place down there because it’s so dark.
“Often I’ve gone past and seen people meeting under the bridge and round there.
“There have been some strange things found over the years. Someone found a nun’s headdress once, and another time someone found a suitcase of clothes.”
The 60-year-old, who has lived in the house since 1981 added that the spot had been a popular place for truck drivers to stop before the Pease Pottage service station was built.
“Gypsies used to camp down there as well. It’s a very lonely place.”
Down the road, in nearby Slaugham, locals in the Chequers pub were shocked by the find.
Colin Pomfret, 74, who was enjoying a lunchtime pint, said: “It’s a bit disturbing to have something as gruesome as that happen down the road.
“It will be interesting to see if they can match it up to the torso they found nearby.”
The pub’s landlord, Alex Tipping, added: “We’re all quite shocked really, especially with it being so close.”
Police taped off a small section where they had spent the evening digging and left officers to guard the scene overnight.
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