26/09/2016 08:54 BST | Updated 26/09/2016 15:30 BST

Ben Needham Dig Begins At Kos Site As His Mother, Kerry Needham, Is Told To 'Prepare For The Worst'

The toddler vanished 25 years ago.

The mother of missing toddler Ben Needham has been told to “prepare for the worst” as excavation work begins in Kos today in the search for possible remains.

Kerry Needham said the notion her son was dead never entered her “worst nightmares” until a mystery tip-off to police earlier this year.

Investigators on the Greek island where the 21-month-old vanished 25 years ago are following a new line of inquiry which suggested Ben may have been crushed to death by a digger near a farmhouse his grandparents were renovating in July 1991.

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Ben Needham's mother has been told to 'prepare for the worst' by detectives who suspect he may have died 25 years ago.

Konstantinos Barkas, also known as Dino, was clearing land with an excavator close to where Ben was playing on the day he vanished and may be responsible for his death, a friend of the builder reportedly told police following a TV appeal in May.

The driver reportedly died of stomach cancer last year, months before detectives from South Yorkshire Police arrived on the island for a renewed investigation.

On Monday, officers began digging up the site where it is feared Ben’s remains could lie.

Gareth Fuller/PA Wire
South Yorkshire Police search officers sift through piles of earth taken from an olive grove near the scene where toddler Ben Needham went missing.

Ms Needham, from Sheffield, told the Daily Mirror: “Not even in my worst nightmares has Ben ever been dead ... until now. I’ve been waking up and finding my pillow wet with tears.

“This witness told police we deserve the truth – but we deserved the truth 25 years ago. I feel like he’s only come forward because Dino is now dead.

“How can you hold on to such a secret as serious as that and for all those years?”

She added she was “angry” when police told her about the tip-off and she now lives in fear that each day will bring the “worst news possible”.

Gareth Fuller/PA Wire
Police use a digger to investigate the olive grove.

A variety of theories on his fate and reported sightings have arisen since his disappearance and Ms Needham had been holding out hope that she would one day be reunited with her son.

Mr Barkas’s widow Varvara strongly dismissed any suggestions her late husband had killed Ben in an accident.

Gareth Fuller/PA Wire
Officers start excavations in relation to the missing toddler Ben Needham.

South Yorkshire Police has confirmed that its team, led by Detective Superintendent Matt Fenwick, will begin searching a specific site on Kos, starting on Monday.

But it warned progress could be painstaking, with the first dig expected to last up to 12 days.

Gareth Fuller/PA Wire
A view of the scene in Kos, Greece.

Detectives carried out initial inquiries at the site prior to the excavation, with experts testing soil and surveying the area with drones.

Last week, Mr Fenwick said: “There will be planned operational activity at two locations on the island that have been identified as areas of interest to the investigation.

“We continue to keep an open mind and have updated Ben’s family about certain lines of inquiry we’re currently exploring.”