A quarry searched as part of the investigation into the mysterious disappearance of Renee MacRae and her son is to be reopened.

A Highland firm wants to extract sand and gravel from Dalmagarry Quarry beside the A9 north of Tomatin.

The bleak area became central to the murder mystery that shocked the north nearly 40 years ago.

Police officers involved in original inquiry believed the bodies of the Inverness housewife and her three-year-old son Andrew could have been buried there.

The quarry was not far from where Mrs MacRae’s burning BMW car was found in Dalmagarry layby.

Another theory was that the mother and son were buried along with toddler Andrew’s buggy under the Inverness-Perth road, which was being realigned at that time.

The quarry was at the centre of a massive search at the time of Mrs MacRae’s disappearance.

And after a cold case review in 2004, it was the focus of an even bigger police investigation when a team of forensic officers dug up the site as part of a renewed search for Mrs MacRae.

No trace of the mother and son was found.

At first the case was treated as a missing persons inquiry, but later the police declared it was a murder investigation.

Now the quarry is to be reopened by Alness-based Pat Munro Ltd – to provide materials for the dualling of the A9, which will start later this year.

Councillors yesterday granted planning permission for extraction and a tar plant, despite claims that access arrangements for heavy trucks were a “danger” to motorists.

Last night, Mrs MacRae’s sister, Morag Govans who lives in Inverness, said she was intrigued at the prospect of the quarry being opened again.

She said: “I don’t have a lot of hope but you just never know. I never thought that quarry would be opened up again.”

The police were unable to comment on the development last night or say if they would be monitoring the quarrying operations.

Mrs MacRae and her son Andrew vanished in November 1976.

Her burned-out BMW car was found in a layby on the old A9 near Dalmagarry – just a few hundred yards from the quarry.

The mother and son’s bodies have never been found despite a lengthy police investigation.

In 2004 Inverness forensic anthropologist Sue Black, of Dundee University, and forensic archaeologist John Hunter, of Birmingham University, led a new search under the supervision of the senior investigating officer.

Brian Munro, managing director of Pat Munro Ltd, said: “Because of the dualling of the A9, there is going to be a shortfall in aggregates needed.

“That is going to be a problem right the way down the A9.

“We want to open up the quarry because of the need for aggregates, concrete and tar.

“That is the primary reason but we hope that it will have a life beyond that.”

He added: “The quarry does have a bit of a history. The police carried out a full excavation of the old quarry works and they were able to eliminate the quarry.

“We hope to open up later this year, in time for the first phase of the A9 works.”

Background: Renee MacRae case

The mystery of Renee MacRae’s disappearance with her son has gripped the north for nearly 40 years and become one of Scotland’s most notorious unsolved crimes.

The 36-year-old and three-year-old Andrew were last seen alive in November 1976.

They were travelling from Inverness to meet Mrs MacRae’s lover Bill MacDowell, an accountant in her husband’s building company.

Her burned-out BMW car was found in a layby off the A9, a mile south of Tomatin.

A bloodstain was found in the boot and eventually a murder inquiry was launched.

But the bodies of the mother and son have never been found and no one has ever been convicted of their killing.

At the time of her disappearance, Mrs MacRae had split from her husband, millionaire company director Gordon MacRae, and was having an affair with Mr MacDowell – a married man who was Andrew’s biological father.

Mr MacDowell has always denied meeting Mrs MacRae on the night she disappeared.

In 2004, Northern Constabulary opened a cold case review and officers carried out an excavation of Dalmagarry Quarry, just a few hundred yards from where the young mother’s car was found.

At the time of her disappearance, the A9 was under construction close to the quarry.

The dig, led by Professor Sue Black, cost about £112,000 and lasted a month. However, nothing was found.

Two years later, the force submitted a report to the procurator fiscal, claiming to have closed an “evidential gap” in the murder hunt.

But the Crown Office said there was not enough evidence to arrest anyone.

In the same year, local farmer Brian MacGregor paid for a radar investigation of the stretch of road near Dalmagarry, and later claimed that this indicated that the bodies might be buried under the newly-built road.