The family of missing Edinburgh academic Fergus McInnes have sent out an emotional message on the day of his 52nd birthday.

His family has fondly recalled memories of the missing research fellow, who disappeared after going to a convention in Switzerland five weeks ago, while also confronting difficult questions.

Police Scotland have been working with their counterparts in Switzerland and Interpol in trying to trace the computer expert, who has a history of mental illness.

He was last seen boarding a train at Geneva Airport bound for Martigny. He may have gone hiking.

The unsigned blog is believed to have been written by sister, Lorna McInnes, from Blairgowrie , who has been providing updates.

It read: "He (Fergus) was born in 1962, the first child to my parents, Bennet and Elizabeth McInnes.

"My mum remembers the day well, recalling that the weather was sunny and crisp, the autumn colours particularly magnificent.

"Edinburgh was bedecked with flags that day, and although this may have had something to do with a visit from the King of Norway, my mum likes to think that they were put up to welcome a tiny Fergus into the world."

She continued: "Fergus went missing last month, aged 51, just over five weeks before his 52nd birthday.

"Much as we would love to celebrate his birthday with him, more than anything else we long to know where he is and what happened to him on September 9.

She asks where he is today and is he "alive and aware of the significance of the date".

She added: "Or, alive but due to some sort of mental malfunctioning, not aware that there's anything important about October 16?

"Alternatively, and this is the option that's hardest to accept, did his life end five weeks ago, aged just 51?

"In some ways, the longer his disappearance remains a mystery the easier it becomes to live with the uncertainty, purely because we've had five weeks of practice.

"In other ways, however, it feels no easier now than it did at the beginning. Sometimes, an intense desperation to know the truth suddenly hits home with a shocking impact.

"Such abrupt reminders of the reality of the situation can be so powerful that they almost take the breath away, and the emotional response can be instant and upsetting.

"I ask myself 'where is he?' and the yearning for an answer is almost overpowering.

"I'm not alone in this, I know other members of my family feel the same way and I'm sure some of Fergus's friends have had similar experiences.

"I wish we had an answer to that most fundamental of questions - where is Fergus?

"Unfortunately, for now, we must continue to exercise patience and remain hopeful and optimistic in what is, at times, an extremely difficult and distressing situation."