Their killer didn't even try to cover-up his crime.
After he'd shot the three victims in the head with a .22 calibre rifle and stripped them of their identification, their pockets turned inside out, he left the three young travellers to decompose in the searing outback sun.
Karen Edwards, Gordon Twaddle and Timothy Thomson were found in the Queensland outback in October 1978 by a couple who were walking their greyhounds.
They were all clothed and, strangely, Edwards was partly covered by a piece of tin. By all accounts the trio didn't see the attack that claimed their lives coming. They were found amid camping equipment and personal belongings which either suggest the killer crept up on them and opened fire or was living with them in the temporary setup.
Decades later — and despite the offer of a $250,000 reward money — authorities had remained baffled by the killing.
But now the mystery may have finally been solved.
A man has been charged with the murders near a bush track at Spear Creek, near Mt Isa.
A 63-year-old, whom the Brisbane Courier Mail reports is former prison officer Bruce John Preston, from Goulburn, has been charged with three counts of murder.
The cold case was likened to a "real-life Wolf Creek", the story of three road-trippers in remote Australia who are plunged into danger.
The three were last seen on the morning of October 5 after their arrival in Mt Isa as part of a motorcycle journey from Alice Springs to Melbourne.
Thomson 31, and Twaddle, 21 were family friends from New Zealand with a passion for motorcycles.
Edwards, 23, was Thomson's girlfriend and the trio were on the adventure of a lifetime trekking across the outback.
Once they reached Cairns, the trio planned to head south to Melbourne for Christmas with family.
They never made it.
After their last sighting in the Moondurra (Moondarra) Caravan Park, their bodies were found 19 days later in bushland near Spear Creek, 12 km north of Mount Isa.
All three died from gunshot wounds.
Preston had been a person of interest, charged with stealing Tim's motorcycle in 1978 for which he was convicted and fined $300.
Detective Senior Sergeant Tara Kentwell said the families of the victims had been told of the charges and were relieved by the outcome.
"We believe that there are still witnesses out there who hold vital information and we appeal for those persons to come forward,' she said.
Kentwell said the accused was "surprised" by the arrest, but would not comment on a motive other than that he was known to the victims before October 5.
Kentwell said it felt "pretty good" to make an arrest four decades after the crime.
"It's a good feeling to provide some closure to these families after such a long time."
The man is expected to face Brisbane Magistrates Court today charged with three counts of murder.
Making of a mystery
Monday, October 2, 1978
: The trio embarked on a motorcycle trek from Alice Springs. Thomson and Edwards were travelling in a red 1977 BMW 100S with a homemade side car carrying Tim's nine-month old Doberman, Tristie.
Twaddle was riding a blue 1977 Suzuki GS750 with Victorian registration plates.
The group travelled to Aileron and camped at Ti Tree in NT overnight.
Tuesday, October 3, 1978: The group stopped at Wauchope, Devils Marbles and The Three Ways. They met a male motorcycle enthusiast at Frewena before camping with him overnight at Barry Caves.
Wednesday, October 4, 1978: The group continued to travel with the man to Mount Isa. Only Edwards, Thomson and Twaddle checked into the Moondarra Caravan Park in the afternoon. On Wednesday evening, the trio were joined by a man in a brown and white Toyota Landcruiser.
Thursday, October 5, 1978: The trio were seen leaving the caravan park with the man in the Toyota Landcruiser, leaving the motorcycles and dog behind.
Later on Thursday, the same vehicle returned to the park with a man seen alone looking for the dog.
Friday, October 6, 1978: All property except for the sidecar was removed from the campsite. The dog was located at the Mount Isa Dump.
October 24-25, 1978: The bodies of the three were discovered in bushland at Spear Creek.
November 13, 1978: A 23-year-old local man was arrested after being found in possession of Tim's red BMW motorcycle.
April 12, 2019: A 63-year-old man, reported to be former prison officer Bruce John Preston from Goulburn, is charged with three counts of murder