Specialist members of the armed forces have been mobilised to help police in their search for the remains of a mother and son who were murdered nearly 50 years ago.
Renee MacRae, 36, and her three-year-old son Andrew were killed by William MacDowell in November 1976.
Married MacDowell, who had been having an affair with Mrs MacRae, was convicted in 2022 but died behind bars at the age of 81 without revealing where he had disposed of their bodies.
A Ministry of Defence spokesperson said the army was supporting Police Scotland and the National Crime Agency (NCA) following a request for "specialist expertise".
The exact location of the search is yet to be confirmed.
Detective Superintendent Brian Geddes, who helped bring MacDowell to justice, said: "Our investigation into the murders of Renee and Andrew MacRae remains ongoing and officers continue to examine all available lines of investigation."
Mrs MacRae and Andrew have been missing since 12 November 1976.
The pair left their home in the Scottish Highlands, with Mrs MacRae's BMW car found later that day on fire in a layby on the A9 near Dalmagarry.
MacDowell and mother-of-two Mrs MacRae had been having an affair for more than four years when she vanished.
Mrs MacRae was estranged from her husband, Gordon, who was MacDowell's boss at Hugh MacRae Builders Limited.
At his trial, MacDowell denied any wrongdoing and was brought to the High Court in Inverness each day in a wheelchair by his wife Rosemary.
However, jurors rejected his claim the killings were committed by somebody else and convicted him of the crimes.
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Judge Lord Armstrong described the murders as "executions" as he handed down a life sentence with at least 30 years behind bars.
MacDowell, an inmate at HMP Glenochil in Clackmannanshire, died at Forth Valley Royal Hospital in February 2023.
Investigations have continued since 1976, with Dalmagarry Quarry extensively searched during a month-long excavation in 2004.
Officers returned to the area last year following the discovery of an item during roadworks on the A9.
In 2019, Leanach Quarry was excavated as part of the probe.
And in August 2023, police said officers were looking into properties linked to MacDowell as well as other places he may have met Mrs MacRae during their relationship.
DS Geddes previously said: "This case will never be considered resolved until we find Renee and Andrew."
(c) Sky News 2026: British Army joins search for remains of mother and son murdered 50 years ago
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