William MacDowell guilty of murdering Renee MacRae and son Andrew in 1976

MacDowell, 80, will spend the rest of his life in prison after being ordered to serve a minimum of 30 years.

William MacDowell has been sentenced to life in prison (Andrew Milligan/PA) (PA Wire)

A married man who murdered his lover and their young son more than 45 years ago will die behind bars.

William MacDowell was sentenced to life in prison with a recommendation that he serve a minimum of 30 years for killing Renee and Andrew MacRae in November 1976.

Police have never found the bodies of the 36-year-old mother or her son, three, with officers now urging the killer to disclose what he did with them so they can be “provided with the dignity they deserve”.

Passing sentence after MacDowell was found guilty of murder at the High Court in Inverness, judge Lord Armstrong told him: “These murders appear to have been premediated, planned and carried out in the most calculated way – not a spontaneous event or spur of the moment.

“These appear, in effect, to have been executions.

“You murdered your victims and then disposed of their bodies and personal effects, including the boy’s pushchair.

“You then took steps to conceal the crimes you had committed.”

As well as being convicted of the murders, MacDowell was also found guilty of attempting to defeat the ends of justice by disposing of their bodies and personal effects.

The jury of seven men and eight women took just under four hours to come to their conclusion, and as their verdict was read out there were gasps in the court room.

Mrs MacDowell, who sat in the public gallery, stared down at the floor and, as her convicted husband was wheeled out of court by security officers, they looked at each other for the last time before he is put behind bars.

The court heard that MacDowell, of Penrith, Cumbria, killed or abducted Mrs MacRae and their son in a layby on the A9 near Dalmagarry, south of Inverness, on November 12, 1976.

Their disappearance was one of the longest unsolved murder cases in Scottish criminal history.

Mrs MacRae’s sister, Morag Govans, said after the trial: “More than 45 years of the pain of losing Renee and Andrew doesn’t ease.

“Not a day passes when both are not in our thoughts.”

The guilty verdict came after advocate depute Alex Prentice KC told the jury MacDowell was the only man with the motive for killing the pair, as his concern grew that news of his affair would be revealed and what that would mean for his finances and lifestyle.

“Life for Bill MacDowell would change dramatically if it all came out in the open. He would lose his job, his family and his home,” Mr Prentice said.

MacDowell and Mrs MacRae – a mother-of-two who was separated from her husband – had been having an affair for more than four years when she vanished, with MacDowell having been questioned numerous times about his connection to the estranged wife of his former boss.

During his first police interview, he refused to admit any association with her, only revealing this in a second interview later the same day.

Even when the case came to trial, MacDowell, who was brought into court each day in a wheelchair by his wife Rosemary, had claimed the crime, if it did happen, was committed by Mrs MacRae’s estranged husband Gordon MacRae and others unknown.

Mr MacRae, who was the director of Inverness firm Hugh MacRae Builders Limited, was asked by the advocate depute if he played any part in the deaths of the pair. The 85-year-old told the jury: “Absolutely none.”

The trial was told that after the couple split, they had an “amicable” relationship, with Mr MacRae aware his estranged wife was involved with someone else and that Andrew was not his child.

He had provided her with a home in Cradlehall Park, Inverness, and with a metallic blue BMW.

The car was found burnt-out at the Dalmagarry layby, south of Inverness on the A9, on the night Mrs MacRae and her son were murdered.

Catherine Johnstone told the court her mother Eva McQueen had heard a “blood-curdling scream” just a few hundred yards from the layby at Dalmagarry Farmhouse.

Mr Prentice told the jury this was the “last utterance of Renee MacRae while alive”.

MacDowell’s company Volvo was spotted nearby, the court heard, the very car he admitted burning part of the boot of.

Ms Govans, now 84, told the trial of her sister’s devotion to her two boys, and said her concerns had grown for her welfare when detectives visited her home after the disappearance.

Ms Govans said: “I was very worried. I knew something dreadful had happened to Renee and Andrew. I knew Renee would never have gone away and left her other son Gordon behind.

“I know Renee wouldn’t have put me through that. She would have contacted me if she had gone anywhere.”