Michael Mosley missing - 6 theories as to what's happened to missing TV doctor

A major search operation for TV doctor Michael Mosley has found no sign of the star more than 48 hours after he went missing. The This Morning star disappeared on the small Greek island of Symi, where he had been holidaying with his wife Clare.

The 67-year-old vanished after walking back to the town of Pedi where he was staying from a nearby beach. CCTV now shows he made it back to the town along the coastal path where it had been feared he may have fell.

Amidst worries that the intense Mediterranean heat could have affected him, a major search was launched with firefighters, police, the coast guard, drones and helicopters all scrambled to look for him. While the overwhelming heat is being considered a factor in his disappearance, authorities are also probing the likelihood of a severe fall or even a snake bite.

Read more Michael Mosley CCTV sparks long shot 'possibility' as it rules out 'fall' theory

Below we look at all the theories being considered as the search continues.

Fall into sea

One theory being explored by Greek officials is that Dr Mosley might have fallen into the sea. Mayor Papakalodoukas said that search and rescue teams found it "impossible" for Mr Mosley tostill be in the area they had combed.

Symi's deputy mayor, Ilias Chaskas, told PA news agency that "divers are looking in the water", with local coast guard forces also joining the search operation. The coast guard of Symi stated: "All our patrol boats are searching... about five and also all the private boats, commercial boats know about the incident and they look for (him) also, in this area, (so this is) the private, the commercial and the patrol (boats looking)."

A senior official informed BBC News: "It is a very small, controlled area, full of people. So if something happened to him there, we would have found him by now".

Heat exhaustion

Heatstroke is another concern raised by Mayor Papakalodoukas, who suggested that the scorching heat could have led to dehydration and caused the doctor to collapse in the rugged terrain.

Dr Mosley set out for his walk at 1.30pm amidst a heatwave, with temperatures on Wednesday soaring to 35C.

Heart attack

A senior police source told the Daily Mail that heart failure could be a factor: "He may have slipped and fallen, perhaps because of a heart attack along the way. Nothing at this stage can be ruled out".

Snake bite

Authorities are not ruling out a snake bite either having injured the star. Symi is home to the Ottoman Viper Europe's deadliest snake.

Although bites are uncommon, the viper's venom is known to be particularly toxic and can be fatal in small quantities.

Lost and disorientated

Concerns are growing that Dr Mosely might have got lost. He had left his phone at the beach before walking to Pedi, meaning he had no GPS navigation.

But locals claim it's "pretty difficult" to get lost on the island nowadays. A source familiar with the area told PA: "I'm having trouble understanding how you could get lost."

Stranded somewhere injured

There are fears Dr Michael Mosley could be lying injured and unable to call for help due to the absence of his phone. A top Greek official coordinating the search efforts disclosed that extensive actions are being taken.

They confided to The Sun: "Since this morning we have had all available forces out there on the island and we have asked to bring in specially trained dogs and even a helicopter from Athens for back up too. No stone will be left unturned. Symi is a small island, he can't just have disappeared."