It was the brutal triple slaying that shocked a nation and still sends a chill down the spines of serving army personnel decades on.
Three of their own lying dead in the blood-soaked snow of the Pentland hills – executed one-by-one and the £19,000 cash wages they were carrying stolen.
Last Friday marked 35 years on from the Penicuik payroll murders and one burning question remains – what happened to the money which was never found?
Cold-blooded killer Andrew Walker, now 65 and thought to be living in a care home, was released on compassionate grounds in 2011 after suffering a massive stroke.
“Each year he lives on, I get angrier,” Susan Thomson, who was 19 when her husband Private John Thomson was gunned down, said last year.
On January 17, 1985, retired Major David Cunningham (56), Staff Sergeant Terence Hosker (39) of the Royal Army Pay Corps, and Private Thomson (25) of the Kings Own Scottish Borderers picked up the payroll from the RBS in Penicuik to take to Glencorse Barracks.
Walker, then a 30-year-old corporal, flagged down their Land Rover for a lift but unbeknown to his victims he was armed with a sub-machine gun he signed out from the armoury.
He forced the three men to drive away from the bank at gunpoint, shooting Sgt Hosker in the chest when he was tackled.
Telling Pte Thomson to drive along a quiet track to a reservoir, he shot Major Cunningham through the head.
Terrified Thomson was then forced to unload the bodies of his colleagues before being shot himself in the head and stomach.
The money was never recovered while Walker was snared by clues he left at the scene after a three-day manhunt.
“He wasn’t that difficult to catch,” a former senior detective revealed.
“There was the gun that he signed out and still had.
“He wasn’t exactly a criminal mastermind, he was a cold-hearted killer.”
With three tours to Northern Ireland and a mention in dispatches, Walker’s army career began successfully, only to turn increasingly erratic with disciplinary issues.
He tried to blame the killings on a terrorist atrocity linked to the Troubles but the jury saw through his crude ruse.
In fact, owing £2,000 on a car bill and about to take delivery of a new motor worth £8,500, he was motivated purely by money.
“We never really found out about his background,” said the former detective.
“There was all kinds of speculation that he was involved in some pretty dark stuff in Northern Ireland.
“It was a robbery, and he was determined just to kill them.”
Walker was sentenced to 30 years in prison, later reduced to 27 years on appeal – yet the mystery of what he did with the loot remains.
“The money is still missing, maybe it’s still buried in the hills,” added the former detective.
“It’s a trifling amount when you consider the loss of life.”