On November 12, 1976 Renee MacRae and her toddler son Andrew left their home in the outskirts of Inverness heading south on the A9.
Later that same day their BMW was discovered on fire beside the road near Dalmagarry, only a few miles south of the city.
Neither Renee, 36, nor Andrew - just three-years-old - have been seen since that night 42 years ago.
The investigation into their disappearance is continued to this day by Police Scotland's Major Investigations Team, using modern forensic and investigative techniques in an effort to provide answers to Renee and Andrew's family.
Speaking on behalf of the family, Morag Govans, Renee's sister and Andrew's aunt, said: "More than four decades on the pain of losing Renee and Andrew doesn't ease. Not a day goes past that both are not in my thoughts.
"Andrew was just three-years-old, 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.
"He would have turned 45 in October and I often wonder what he would have been doing now with the life that he was never given the chance to build.
"Renee was a compassionate and caring mother. Both Andrew and his elder brother Gordon were her life. She adored them and was so proud of her boys.
"Gordon was only eight and has lost the love and guidance of his mum and brother.
"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.
"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."
Detective Inspector Brian Geddes said: "The circumstances around the disappearance of Renee and Andrew MacRae are currently subject to review by detectives from Police Scotland's Major Investigations Team who are pouring through every single item we hold in a bid to identify new lines of enquiry and develop any existing lines of enquiry where there is potential to progress them further.
"All the indications are that Renee and Andrew came to harm 42 years ago and as such this is being progressed as a murder investigation.
"The initial investigation and the various reviews and re-investigations since 1976 appear to have been very thorough and have generated a great deal of material.
"We are applying the most modern investigative techniques in a bid to progress the investigation and this will include utilising advances in forensic science.
"Our goals are to bring a person, or persons, to justice and to locate the remains of Renee and Andrew in order to bring some form of closure to Morag and the rest of the family.
"We will draw on the investigative expertise from within our organisation and beyond, and I have assured Morag and her family that everyone involved in the investigation is fully committed and will leave no stone unturned in a bid to find the answers the family deserve.
"The chances are that person or persons responsible for the murders of Renee and Andrew will have enjoyed a life, something which was denied to Renee and Andrew.
"With that in mind I would again appeal to anyone who has information, even if they are not sure if it is important, to come forward and contact us.
"Specifically, I want to take this opportunity to appeal to someone who wrote anonymously to Northern Constabulary in 1982 regarding information surrounding activity at an unnamed quarry on November 12, 1976.
"It appears that this person had moved away from the area in the subsequent years. If you recognise yourself as the writer of this letter then I urge you to get in touch with the investigation team.
"Forty-two years is undeniably a long time, however, it is certainly no barrier to justice.
"Someone out there knows what happens to Renee and Andrew and I hope this appeal today serves as a reminder that it is never too late to come forward with information."
"Anyone who believes they can assist Police is asked to contact 101 or you can e-mail a dedicated inbox at SCDHOLMESInverness@scotland.pnn.police.uk.
“You can also contact Crimestoppers anonymously on 0800 555 111."