The search for the bodies of a mother and her son is set to focus on buildings linked to the man convicted of their murders and places they met during their relationship, police have said.

William MacDowell was last year found guilty of the murders of Renee and Andrew MacRae, who have been missing since November 12, 1976.

They had left their home in Inverness and the car owned by 36-year-old Mrs MacRae – with whom MacDowell was having an affair – was found later that day on fire in a lay-by near Dalmagarry.

Renee MacRae, 36, and three-year-old Andrew. Picture: PA

MacDowell was sentenced to life in prison in September last year, but he died in February. The bodies of Mrs MacRae and three-year-old Andrew have never been found.

Police have launched another appeal for information, saying a review is looking at properties linked to MacDowell or any places he may have met Renee during their relationship.

MacDowell and Mrs MacRae had been having an affair for more than four years at the time of her disappearance.

Detective Chief Inspector Brian Geddes, who helped bring MacDowell to justice, said: "Renee and Andrew's family and friends waited decades for justice, which was served last year.

"However, their bodies have not been found and our investigation continues to explore all possible opportunities open to us to help answer that final, most important question in order to provide Renee and Andrew with the dignity they deserve.

"We continue to review the available evidence to identify any further areas of interest, while also considering whether there are any opportunities that modern technology could assist with in identifying possible deposition sites.

"This review includes considering any properties which may be linked to William MacDowell which he could have used, possibly a derelict building, an empty one or even an occupied one he had use of.

"The timescale would be the early to mid-1970s and we are hoping someone may remember seeing Renee MacRae's BMW car in an area, perhaps with MacDowell's company Volvo or the family white Range Rover.

"We are also considering possible sites where they may have met during their relationship, possibly including the Blackfold area above Loch Ness, Inverfarigaig, and between Nairnside and Daviot.

"This case will never be considered resolved until we find Renee and Andrew.

"We owe it to the family and friends to make every effort to recover Renee and Andrew's bodies and I would urge anyone who may be able to assist, no matter how small you may feel your information is, to come forward."

As well as being found guilty of murder, MacDowell was also found guilty of covering up his crimes by disposing of Renee and Andrew’s bodies and destroying evidence.

A huge police investigation was launched after their disappearance, with road blocks set up on the busy A9 in an attempt to find as many witnesses as possible. But despite this, and investigations in 1986, 2004 and 2018, the remains of Renee and Andrew have never been found.

Anyone with information is asked to call police on 101.

Review of 1976 Scottish murders of Renee and Andrew MacRae to focus on derelict buildings