A week after Guy Fawkes Night 28 years ago, an empty BMW was found ablaze in a darkened lay-by. The only clue to what had happened to its occupants - Renee MacRae and her three-year-old son Andrew - was a spot of blood in the boot.
The murder of the wealthy businessman's 36-year-old wife and her child has remained one of the most enduring conundrums in Scottish criminal history. Hundreds of police officers, forensic scientists, hypnotists, journalists, mediums and psychics have all attempted in vain to discover the truth.
But yesterday the Northern Constabulary announced the latest chapter of the mystery. Its officers, it revealed, had begun clearing the undergrowth around a disused quarry.
If, as one retired Detective Sergeant is "99.99 per cent" convinced, the two bodies are at the site close to the lay-by it may finally solve a puzzle which should have been solved three decades ago. John Cathcart, a CID officer at the time, insists he smelled rotting flesh at Dalmagarry Quarry during a 1977 dig but the search was called off.
On the other hand, if the quest proves fruitless, it will be yet another dead end in one of the country's most notorious unsolved crimes.
"I think about it every day. Every time I hear of remains being found in the Highlands. I think ... 'this is it'," explained retired Detective Inspector Donald MacArthur, the man who led the hunt in 2001. He died six months later, convinced he had spoken to the murderer and ever-hopeful that one day justice would be served.
Yesterday Detective Superintendent Gordon Urquhart, who helped with the initial search and current head of the inquiry, said: "We are now in a position to say from [existing evidence coupled with new expert advice] that there is a reasonable chance there will be something available for us, so hopefully we will find remains."
The early investigation was, in the words of one of senior officer, mired in "a sea of deceit and untruthfulness" from its start in 1976.
Mrs MacRae, who had grown up in a council house in Beauly and worked at Boots, had married well. Gordon MacRae's company had a turnover of £30m a year and the couple enjoyed a comfortable lifestyle in Inverness with what most believed to be their two sons.
But five years into the marriage the "attractive and fun" housewife had begun an affair with her husband's secretary Bill MacDowell and it would later emerge that he was the father of the youngest son, Andrew.
By November 1976 the MacRaes had separated and he was already living with another secretary, who he would later marry, although he continued to think of his wife as a "good friend and wonderful person".
On the morning she disappeared - 12 November - Mrs MacRae had coffee with friends and dropped her older son Gordon, nine, off at school. She was last seen alive when she visited her husband's company at 5pm.
She had told friends that she was planning to spend the weekend in Perth with Mr MacDowell and was hoping that they would soon be making a new life together in the Shetland Isles. But some later remarked he was not as besotted as she was.
Two hours later, the BMW was spotted in a dark lay-by next to the A9, 12 miles south of Inverness. A couple of hours later it was in another lay-by a few miles further south, in a ball of flames. Both mother and son were gone. The fire and equipment used to douse it destroyed most of the evidence. Police initially considered that Mrs MacRae may have simply gone for an illicit weekend and her car was vandalised or she had staged her own disappearance, intent on starting a new life.
But the missing person's inquiry soon turned into a murder investigation. Hundreds, of police, volunteers and soldiers scoured the dense wilderness amid freezing weather and blizzards. At the height of the year-long hunt, tracker dogs and frogmen were enlisted while helicopters with heat-seeking devices flew over the Highlands.
In the early days Mr MacDowell - a suspect who would later be interviewed by police - insisted mother and son were still alive as he had received coded telephone signals to arrange a secret rendez-vous.
Following intense media speculation, the accountant broke his silence and admitted that Andrew was his son and that he had discussed leaving his wife to start a new life with his boss's spouse. He had made a tentative arrangement to meet Mrs MacRae that weekend but changed his mind, he said. This was to be the last time he would make such public comments. He remained with his wife but was sacked from the company. In 1993 he was fined £750 for fraud. Inverness Sheriff Court heard that the offence happened while he was on parole from a 30-month jail sentence in Sussex, imposed for a substantial earlier fraud. Now in his 60s, he lives in south-west London, and yesterday refused to comment on the developments.
Meanwhile, a team of diggers began clearing trees in the quarry near Tomatin in anticipation of a team of forensic anthropologists, archaeologists and scientists, who hope to start a search in a fortnight.
The search will be led by Professor Sue Black OBE, of Dundee University, who investigated war crimes in Kosovo and has had a fascination with the MacRae case since she was a schoolgirl, and John Hunter, of Birmingham University, a leading UK expert who helped in the hunt for victims of the Moors Murderers.
The case has been reviewed several times over the years but this time the police insist there is a "specific reason" to suspect mother and child may be found.
Chief Constable Ian Latimer gave his assurances yesterday that if remains were discovered he would ensure "that the criminal inquiry progressed with the aim of identifying, reporting and prosecuting the killer."
For Morag Govans, 66, who still thinks of her sister all the time, the years have dissolved any hope she had that the killer would be brought to trial.
She said recently: "I don't really care about who did it anymore. All I want is for the bodies to be found. I think that would help, if they got a proper burial and I had a chance to say goodbye."Reuse content