BONES and parts of a pushchair have been found at a flooded quarry being probed by police in the search for a mother and son who vanished more than 40 years ago.

Renee MacRae and three-year-old Andrew were last seen driving out of Inverness on November 12, 1976.

Officers have been searching Leanach Quarry, which has been drained of water, in the latest development of what is now being treated as a murder investigation.

It is understood that among the items recovered are pushchair wheels similar to the Silver Cross model used by Mrs MacRae, which has also never been found.

So far the bones uncovered from the bottom of the quarry, which has been emptied of 13 million litres of water, have been identified as belonging to animals.

But forensic anthropologists are continuing other as-yet unidentified skeletal remains. Mud, silt and material from the quarry is being dug out and taken to an off-site location where a 16-strong team is carrying out a fingertip search.

HeraldScotland:

Officers have drained the territory

Detective Inspector Brian Geddes, who is leading the investigation, said: "As part of the search operation at Leanach Quarry numerous items have been found to date, many of which have warranted further research and examination.

"Meticulous analysis is now ongoing to establish if any of these items would be relevant to the investigation into the murders of Renee and Andrew MacRae."

READ MORE: The disappearance of Renee MacRae - A timeline of events

The site was previously deemed too dangerous to search using divers, but police are “extremely confident that vital evidence” will be found after what has been described as “fantastic progress”.

The disappearance of Mrs Macrae and Andrew remains one of Scotland’s longest-running missing person investigations, and police have long believed they met with foul play.

The mother-of-two led a tangled love life, and was said to be on the way to meet her lover, Bill MacDowell, who was employed as an accountant with her estranged husband Gordon’s building firm.

Mr MacDowell, who provided police with an alibi for the night she disappeared, later admitted he was Andrew’s father. Mr McRae also provided police with an alibi.

Mrs McRae vanished after dropping off her eldest son, Gordon junior, with her estranged husband in Inverness, and leaving with Andrew for Perth.

Later than night, her car was found on fire on a loop road which was being used as a lay-by during the construction of the new A9 trunk road.

HeraldScotland:

Ms MacRae's car was burned out

Blood was uncovered in the boot of the car but there was no sign of the mother and son, and police began investigating.

In the fortnight which followed, more than 100 police officers and large numbers of volunteers searched moorland around the site of where the car was discovered, while RAF Canberra aircraft made wider sweeps of the area.

The quarry has previously been the subject of police interest. In 2004, a full cold case review resulted in a month-long excavation of Dalmagarry Quarry.

READ MORE: Police to drain Leanach Quarry in search for Renee MacRae​

Several days were spent at Leanach Quarry last October when officers released an image of young Andrew around the time of what would have been his 45th birthday.

Gordon MacRae, now 55, recently appealed to police to find his mother. He said: "I want them to keep going until they find something. People say you’ve got to carry on with life, but it’s hard.

“It’s haunted me. I think about them practically every day but I’m good at hiding it and putting on a smile and a brave face.

"But it would settle my mind if I knew what had happened to them.”

HeraldScotland:

Police released a picture of the pushchair Mrs MacRae was using

Mrs Macrae’s sister, Morag Govans, has also previously made an appeal for information which would lead to the mystery of her sister’s disappearance being solved.

She said: “Not a day goes past that both are not in my thoughts. Even after the passage of time I believe that there are people who know what happened to Renee and Andrew, and I will never give up hope of getting justice for them both.

READ MORE: Quarry may hold ‘vital evidence’ in search for mother and son missing since 1976​

“I appeal for anyone with any information to come forward and for others to examine their conscience to end 42 years of pain and anguish to allow us to grieve for Renee and Andrew.”

She added: “Andrew was a mischievous and fun-loving wee boy. It is impossible to take in that his life was brought so cruelly to and end at such a young age.

“I often wonder what he would have been doing now with the life that he was never given the chance to build.”