THE sister of a missing academic has said she hopes the mystery about his disappearance will be solved in 2015 - but she believes he must be dead.

Fergus McInnes, a fellow at Edinburgh University and a keen hill walker, went missing on a trip to Switzerland in September.

On New Year's Day his sister Lorna McInnes posted a moving update on the web page which family and friends set up to share information about him.

Ms McInnes said her brother, who has a history of mental illness, had chosen to spend every previous Christmas and usually New Year with her parents. She wrote: "It is pretty well inconceivable to me that Fergus would choose not to be at home at Christmas. He always enjoyed this time of year, the excitement of giving and receiving presents, eating together, and going for walks on crisp frosty days. Even at his lowest point in 2009, he was at home and willing to join in the festivities as well as he could."

Stressing she cannot speak for anyone else, Ms McInness said that she has come to believe her brother, 51, is no longer alive.

She explained: "To some people it might look as if not enough time has passed for us to come to this conclusion. It is, after all, less than four months since he went missing. If he had taken himself off for a break, it's possible that he could disappear for several months without contact. I agree with that in principle, but knowing Fergus as I do I find it nigh on impossible. He has always been keen to communicate, whether online, as has been the case in recent years, or by other means."

Ms McInnes described how difficult it was for the family to live with the ongoing uncertainty. She said: "What we want, indeed what we feel we need in order to carry on with our lives, is some sort of evidence of what happened to him. The Swiss police have not been able to trace him in the area where he's believed to have gone missing. It is, as we've mentioned before in these updates, mountainous and difficult terrain. Anyone meeting their end in such country could certainly disappear without trace, and the longer time goes on the less likely it is that any remains would be found."

Police Scotland have been working with their counterparts in Switzerland and Interpol to try to trace Mr McInnes, a computer expert.

Previously, Ms McInnes has said her brother may have decided to walk five miles from Martigny in Switzerland to a museum in the village of Salvan dedicated to Nobelprize winner Guglielmo Marconi.