An autopsy report released Monday revealed that Dr. Michael Mosley died of natural causes. However, a physiotherapist told the Daily Express US the case “fits the bill” for heat exhaustion.

The beloved TV doctor was found dead on Sunday after a four-day search amid high temperatures, involving police, firefighters, divers and a helicopter. His wife alerted local police on the Greek isle of Symi that he was missing after he did not return from a walk at Agios Nikolaos beach on Wednesday.

The autopsy revealed that the 67-year-old father of four died around 16:00 on Wednesday of natural causes as no initial injuries were discovered. Separate toxicology and histology reports have also been ordered.

Additionally, Mosley found himself in difficult environmental terrain, where the landscape was rocky and hilly.

All of these factors contribute to raising the body temperature with no ability to cool off.

To make matters worse, Mosley did not have immediate access to shade or water.

As a result, Mosley had no way to lower his body temperature. Those circumstances, Byrne explains, can lead to potentially lethal heat stroke.

“[It was] not a good situation what was happening,” Byrne said of the circumstances of Mosley’s death.

“You wouldn’t recommend someone walking in 35 degree [C] heat with no water at an advanced age with no access to shade, walking over uphill rugged terrain and not knowing the end point,” Byrne said. “[It] is really a recipe for disaster.”

“We don’t know what went on exactly but looking at the details [reported in the press] I would say it fits the bill for exertional heat illness. … Walking for three hours in that sort of environmental condition is not advisable.”

Byrne concluded: “It looks like he made some mistakes, took some wrong turns, ended up on rugged terrain, walking uphill, couldn’t seek shade, no access to fluid, and it’s just real tragic circumstances.”