Police have said they are confident they will find the remains of a murdered mother and son if they have been left in a quarry, as a search of the area nears completion.

Renee MacRae was last seen driving out of Inverness with her three-year-old boy Andrew on November 12 1976.

The 36-year-old mother-of-two’s BMW was found burned out in a lay-by on the A9 near Dalmagarry, 12 miles south of the city, but the pair were not seen again.

No-one has been charged over their deaths.

Leanach Quarry, east of Inverness, has been excavated as part of the murder investigation, with more than 100,000 tonnes of earth, silt and other material removed since work started in May.

The excavation phase is expected to be completed this week, with 5,000 tonnes of material to be forensically searched for evidence.

Detective Inspector Brian Geddes said: “The forensic search of the quarry has been a significant undertaking.

“We have almost completed the excavation process but there remains a vast quantity of material that still requires to be sifted and thoroughly searched.

“This is likely to take a number of weeks to complete but we are confident that if the remains of Renee and Andrew, or any other key pieces of evidence, were disposed of in the quarry, we will find them.

Renee and Andrew MacRae missing
Renee MacRae and her son Andrew disappeared in 1976 (Police Scotland/PA)

“The process of back-filling sections of the quarry where excavation has taken place has commenced and again this will continue over a matter of weeks.

“I would like to thank everyone that has been involved in the operation to date, and the surrounding community for their patience while this has been ongoing.

“We remain determined to bring this matter to a successful conclusion and we continue to progress all relevant lines of inquiry.”

In June pushchair wheels were found during the search of the quarry.

In 2004, a cold case review resulted in a month-long excavation of Dalmagarry Quarry.

Police are urging anyone with information relating to the inquiry to contact them on 101 or by emailing SCDHOLMESInverness@scotland.pnn.police.uk.