SWISS police today admitted they had scaled down the search for missing Fergus McInnes and had no clues to his whereabouts almost a month after his mystery disappearance.
Authorities in Geneva are no longer actively searching for the Edinburgh University academic and are instead waiting for new leads before restarting the hunt.
They say anything “is possible”, but that they currently have no solid information which would give his family in Edinburgh hope.
Mr McInnes, 51, went missing while travelling to a conference on September 9. He was captured on CCTV arriving in Geneva Airport where he bought a return ticket to the Alpine town of Martigny, 50 miles away.
There have been no confirmed sightings since then and police are still not sure if he boarded the train and reached Martigny where the conference was due to be held.
Jean-Marie Bornet, chief of information for the Valais Police, said Mr McInnes could be in Geneva or Martigny, but that it was equally possible he had gone on to Chamonix.
He said “all situations are possible”, but refused to speculate about what may have happened.
“Sometimes people go missing and are found years later,” he said.
While it is understood some searches have been carried out on mountain paths around Martigny, police said they need more specific intelligence before beginning targeted searches.
On Missing Fergus, a blog set up by friends, the latest post says: “It appears that they [the police] are still as puzzled as we are.”
Speaking on her blog, sister Lorna McInnes said the family was “utterly mystified” by her brother’s out-of-character disappearance.
“With a lack of clues about where he might have gone or what might have happened to him, we fall back on endless and wide-ranging theories.”
Mr McInnes, who lives in St Leonard’s and works at the university’s school of informatics, had been expected at the technology conference in the Idiap Research Institute on September 10.
The alarm was raised when conference organisers contacted his colleagues in Scotland. The Foreign Office has been in touch with the Swiss police, and has given assurances that the hunt continues.
A Police Scotland spokesman also confirmed that the force was still passing on information to their Swiss counterparts in Valais and Geneva “as and when” it was needed.
They urged anyone with information to call them on 101.
It has been suggested that Mr McInnes may have gone hiking, but this was dismissed after it emerged he had left his walking boots at home, and would have been ill-equipped for a mountain trek.
Last week his father Bennet McInnes speculated that he may have been violently robbed, or that a traumatic experience had led to amnesia.
Retired Mr McInnes, who worked for the Royal Observatory Edinburgh, denied that his son, who has battled depression in the past, had been “under exceptional emotional strain” at the time of his disappearance.