The farmer who sparked the new search for missing schoolgirl Arlene Arkinson has said he found what looked like a shallow grave.
Noel Doherty, who rents the remote piece of land being examined by forensic experts, said it appeared a hole had been dug and then filled with stones.
He said: "I found this thing of stones about six foot long and three foot wide.
"It is like a grave but I don't know if it's a grave.
"There is something peculiar."
A team of specialists from England have spent much of the day looking at the site close to where the schoolgirl was last seen in the company of convicted child killer Robert Howard.
Their work has been focussed on an isolated patch of land at the foot of a small valley close to the village of Killen, Co Tyrone, several miles outside Castlederg.
Mr Doherty, who has lived and farmed in the area all his life, said the community had never forgotten the teenager who vanished 22 years ago.
"I didn't pass no remarks on it when I saw it first," he said. " But I started to think on it that evening.
"I could see where somebody dug out the clay and back filled it with stones. I thought it was peculiar looking so decided to do something about it.
"I phoned the landowner to find out if any animals had been buried in the garden and he checked it out. There were never any animals buried in that garden.
"It would be nice for the Arkinson family if they could find her but, I can't say what it is."
Access to the scene has been sealed off since Tuesday.
A police cordon has been erected at the top of the single narrow track which leads through fields to a secluded derelict stone farmhouse concealed behind a clump of mature trees.
A run-down metal barn is also behind the police tape.
Experts dressed in white forensic suits have spent much of the day inspecting the isolated site, clearing debris such as branches and twigs and placing a number of items into exhibit bags.
Mr Doherty said his disturbing discovery was about 15 metres (50 feet) to the back of the old house.
Arlene, 15, disappeared in August 1994 after a night out across the Irish border in Co Donegal.
She was last seen being driven down Scraghy Road, close to where the new search is being conducted, late at night with paedophile Robert Howard.
It is believed grazing cattle may have eaten away nettles and grass to reveal the suspicious plot.
"It was all overgrown but the animals ate off the overgrowth," said Mr Doherty. "We always grazed that part of the farm with sheep before and the last couple of months we have grazed it with cattle.
"And, that's how it could be seen - the cattle ate off the nettles and grass and I could make out the stones.
"It could be seen easy enough when they ate the overgrowth but I had never seen it before."
The Police Service of Northern Ireland said the Arkinson family have been made aware of the new activities as a "precautionary measure".
Detective Chief Superintendent Raymond Murray said: "It would be premature to draw any inference from this initial report or the police response to it at this time."
Howard was acquitted of Arlene's murder in 2005 by a jury that was not made aware of his lengthy criminal history which included killing another teenager, Hannah Williams, in south London several years earlier.
However, he remained the prime suspect in the unsolved case until his death in an English prison last year.
There have been more th an 40 extensive searches conducted in forested areas, fire dams, reservoirs and remote farmland in Counties Tyrone, Fermanagh and Donegal but so far, Arlene's body has not been recovered.
Howard's flat at Main Street in Castlederg, the home of Donna Quinn - one of the last people to see Arlene alive - and, controversially, a house belonging to Kathleen Arkinson, a sister of the missing schoolgirl, have also been examined as part of the police investigation.
After receiving a tip-off that Arlene's body was buried under a bridge near a bog, a new team of experts and a victim recovery dog spent months scouring the rural hinterland between 2010 and 2012.
But again, searches at 13 sites proved fruitless.
Meanwhile, a long-running inquest into the circumstances of Arlene's disappearance is expected to conclude hearing oral evidence when it resumes in Belfast on Monday.
Kathleen Arkinson has said she will never give up hope of finding her sister's remains.
She said: "It has been very difficult few days. But I am trying not to raise my hopes up.
"It has been so long and there have been so many let-downs.
"The difference this time is it's so close to where Arlene was last seen. We just don't know what to think, to be honest.
"The timing is also unbelievable, in the middle of the inquest.
"We'll never get justice for Arlene, justice has evaded her in every way, but I hope they can find her and we can get some closure."