Dr Michael Mosley might have 'collapsed with the heat' during his walk through 'treacherous' terrain on the island of Symi, the Greek mayor has claimed.
Mayor Eleftherios Papakalodouka said searchers had been looking in the wrong place for the first two days of the hunt to find the missing Mail columnist who was last seen on Wednesday afternoon.
Dr Mosley, 67, was on the secluded St Nicholas beach when he set off to walk to the town of Pedi from where he was expected to catch a bus back to his villa in the port of Symi.
But the CCTV footage taken in Pedi at about 2pm shows him heading for the mountains instead.
Since then – and despite a massive search operation involving dogs, drones, helicopters and divers – there has been no sighting of the writer and broadcaster.
MrPapakalodouka said Dr Mosley had no water with him when he set off, telling the Sun on Sunday: 'You cannot survive in this weather.'
CCTV appears to show Dr Michael Mosley walking towards rocky hills
Dr Michael Mosley with his wifeClare Bailey, who last saw her husband on Wednesday
Dr Mosley was on the secluded St Nicholas beach when he set off to walk to the town of Pedi from where he was expected to catch a bus back to his villa in the port of Symi
He added: 'We're almost sure he walked into the hills [...] with no shade. If you ask me I think he collapsed with the heat. It was just too much.'
Previously, the mayor had expressed concern that Dr Mosley may have been bitten by a snake.
Symi is home to the Ottoman Viper, which is one of Europe's most deadly kinds of snake.
Rescue teams desperately hunting for Dr Mosley are now focusing their search on a dangerous cave complex known as The Abyss.
Their efforts in the network of caverns and 'endless' underwater tunnels on Friday found no trace of the TV medic, but his wife Clare Bailey has vowed the family will 'not lose hope' of finding him.
Greek police on Friday released new CCTV footage of Dr Mosley taken on Wednesday afternoon, the day he vanished on the island of Symi.
He was carrying an umbrella to protect himself from the 35C (95F) heat and walking purposefully towards a mountain trail.
This is the picture of Dr Mosley posted with an appeal after he went missing while walking on holiday in Greece on Wednesday
A rescue helicopter joined the search yesterday, seen here hovering over Pedi
Speaking yesterday for the first time since her husband's mysterious disappearance, Dr Bailey spoke of the 'longest and most unbearable days for myself and my children'.
In a statement yesterday Dr Bailey, 62, said: 'It has been three days since Michael left the beach to go for a walk. The longest and most unbearable days for myself and my children.
'The search is ongoing and our family are so incredibly grateful to the people of Symi, the Greek authorities and the British Consulate who are working tirelessly to help find Michael. We will not lose hope.'
Sources told The Mail on Sunday Dr Bailey had been called in again to give rescuers further details about what her husband had with him when he disappeared.
An official said: 'It's been four days and no trace has been found of him so it was just to go over things again.
'She explained he was wearing a khaki backpack and had his wallet, bottle of water and a watch, which was not a smart watch.'
On Friday, the couple's four grown-up children travelled to Symi to join their mother.
Volunteers walk mountain paths on Symi where Michael Mosley may have gone after disappearing on Wednesday
They were understood to be part of the search party yesterday scouring the two-mile path from Pedi to Agia Marina, as small beach near The Abyss, where rescue efforts will continue today.
To enter those treacherous caves, Dr Mosley would have to have swum from the Agia Marina beach – the same way the coastguard and divers accessed them yesterday.
Rescuers have also been searching around a separate rocky path close to Agia Marina, which rises across jagged limestone terrain and leads by a longer route back to Symi. But it is not marked and guidebooks warn it is a 'technically difficult' trail.
The Mail on Sunday walked a section of this path this weekend and, although manageable, it would certainly be hard work under a fierce sun.
One member of the search team who we encountered said: 'We have footage of him going this way from the last house in Pedi.
'This is a difficult walk at the best of times and should not be done between 11am and 5pm. We think he was here during the hottest part of the day, at 2pm.'
Rescuers are concerned for Dr Mosley's welfare because of the dangerous heat and described the hunt as a 'race against time' with every minute invaluable.
All boats have been asked to keep an eye out for him in the water and in a sign of how urgently they were treating the situation, firefighters who had been tackling blazes on the nearby island of Kos were transferred to Symi after bringing the flames under control.
At the purpose-built Agia Marina, beach, staff told The Mail on Sunday police had asked to check their CCTV.
One employee said: 'I'm pretty certain I would have remembered a man with an umbrella but no one came this way dressed like that.
'It's a climb to the top of the mountain, then you walk down and it climbs again before you meet a road taking you into the town. It would take about an hour, hour and a half maximum.
'There is nothing between here and Symi apart from stones, more stones and sheep and goats. It's all exposed and I wouldn't try and walk it in this heat.'
