The family of a mother and son murdered 40 years ago say they cannot give up hope their killer will be brought to justice.

The disappearance of Renee MacRae and her three-year-old son Andrew on November 12, 1976, remains one of Scotland's most notorious cold cases.

They were last seen shortly after leaving their home in Cradlehall in Inverness and their bodies have never been found.

Speaking on Thursday, their family appealed to anyone with any information about their disappearance to contact police.

They said: "Forty years have passed since the disappearance of Renee and Andrew and as a family we remain collectively heartbroken to have lost a much loved and cherished mother, sister, brother and friend to many.

"We cannot give up hope that somebody holds information which could help lead us to the answers as to what happened to our beloved Renee and Andrew. Our message is it is never too late.

"We are confident these answers will come from the local community and as a family we urge that person to come forward - until such time the person who caused harm to Renee and Andrew will continue to escape justice and we will be without closure."

When Ms MacRae dropped her eldest son Gordon off with her estranged husband on the night of her disappearance she claimed she was planning to visit her sister in Kilmarnock.

She actually intended to meet her secret lover Bill McDowell, who was Andrew's real father. Mr McDowell has denied any involvement in her death.

Hours later, Ms McRae's burning BMW was found in an isolated lay-by off the A9, which was then under construction.

Bloodstains on a rug found in the boot of the car were a match for Ms MacRae and her son, leading police to treat their disappearance as murder.

A local farmer who believed the 36-year-old had been buried under the A9 commissioned a radar survey, which found an anomaly below the surface of the road.

It was later ruled out as that section of A9 was not under construction at the time.

Detective superintendent Jim Smith, from Police Scotland's northern major investigations team, said: "We will investigate any information received about the murder of Christine and Andrew MacRae.

"There has recently been information within a number of media articles regarding a ground penetrating radar (GPR) report carried out on a stretch of the A9 near to the lay by where Mrs MacRae's car was found burnt out.

"Enquiries have established that the area where the GPR report has indicated an anomaly in the road surface, was not under construction at the time of the disappearance of Renee and Andrew, and it was a considerable period of time before that construction work actually commenced."

The same spot will be dug up during duelling work on the A9 and police say they plan to liaise with contractors.

Ms McRae's sister, Morag Govans, said: "I never ever thought it would take 40 years.

"It's not getting easier because I'm getting older and I wonder whether I'm going to live to see somebody brought to justice."