Christina ‘Renee’ MacRae 36, was last seen driving out of Inverness with her child Andrew, aged three, on November 12, 1976.
It is alleged that William MacDowell, 79, assaulted Andrew and Ms MacRae at the Dalmagarry lay-by at the A9 trunk road, Dalmagarry or elsewhere on that date and that he caused them injury by unknown means, as a result of which they died, and murdered them.
He is also charged with attempting to defeat the ends of justice by disposing of the two bodies and their personal effects by means unknown to prosecutors.
MacDowell, 79, is accused of disposing of a pushchair, setting fire to a BMW vehicle and disposing of a boot hatch from a Volvo vehicle to conceal the alleged crimes and avoid detection, arrest and prosecution.
The 79-year-old, from Penrith, Cumbria, did not appear at the hearing at the High Court in Glasgow in person on Monday for medical reasons.
His lawyer, Murray Macara QC, entered not-guilty pleas to all charges on his behalf and lodged special defences of alibi and incrimination.
Mr Macara said that more than 1,500 people provided statements in the case and work needs to be done to establish which of these witnesses are still alive.
Advocate Depute Alex Prentice QC, prosecuting, said it was not known how long a trial would last, though he tentatively suggested it could be around 15 days, but said this may be “wholly unrealistic”.
He said: “This is a case which arises from events in 1976 and the volume of papers and other material is extensive.
“There has been very good co-operation between the Crown and the defence.”
The Crown has suggested the trial could be held in Inverness and that a jury could be beamed in from elsewhere, but the location of the trial has not yet been decided.
Lord Matthews continued the case until a further hearing on July 22.