The unsolved murders of three friends on an outback adventure almost five decades ago are being re-examined with information uncovered by cold case detectives.

Karen Edwards, 23, Tim Thomson, 31, and Gordon Twaddle, 21, disappeared on the trip of a lifetime in 1978 after leaving Alice Springs with their dog “Tristie”.

Travelling on motorbikes, the three best friends planned to travel down Australia’s east coast to spend Christmas with loved ones in Melbourne.

Their journey ended in tragedy with the gruesome discovery of their bodies near a dry waterway in remote bushland at Spear Creek, 12 kilometres north of Mount Isa in October, 1978.

After almost 47 years to the day, family and friends returned to the Brisbane Coroners Court hoping for answers. 

An inquest in 1980 failed to provide closure, finding “unknown person or persons” were responsible for the triple murder. 

Coroner David O’Connell reopened the inquest today to explore the original evidence and information from a cold case investigation.

The last known sighting of the three friends was at the Moondarra Caravan Park in Mount Isa on October 5 when they were seen with an unidentified man driving a brown and white Toyota Land Cruiser. 

Thomson’s decomposing remains were later discovered by a couple out for a walk at Spear Creek on October 24, 1978, counsel assisting Amelia Hughes said. 

It would be another day before the remains of Edwards and Twaddle were found hidden nearby in a clump of Spinifex grass.

Post-mortems revealed all three had been executed with a bullet to the head fired from a .22 calibre weapon.

“When the bodies were first discovered, they were already in an advanced state of decomposition, and police were not able to identify them straight away,” Hughes told the coroner. 

It was only after the police launched a nationwide appeal to identify a lady’s watch found at the scene that authorities were able to identify Edwards through dental records. 

Forensic officers needed fingerprint evidence to positively identify Thomson and Twaddle. 

The mystery deepened when Thomson’s dog Tristie was found abandoned at the Mount Isa dump, along with their motorcycle helmets and personal belongings, hidden in a 44-gallon drum. 

Twaddle’s motorcycle was abandoned at a Mount Isa service station with the keys still in the ignition, while Thomson’s red BMW bike was discovered at the home of local man, Bruce John Preston.

Preston, who was also travelling around Australia in 1978, admitted stealing the BMW bike and was fined $300, but was not initially linked to the murders. 

Cold case detectives would eventually charge Preston with three counts of murder in 2019, only to drop the case in 2023. 

Preston has agreed to give evidence at the inquest. 

The hearing has accepted the cause of death findings that Edwards, Thomson and Twaddle had been shot in October 1978.

“We are satisfied that the person responsible for this heinous crime is a dark-haired, bearded man in the Toyota Land Cruiser station wagon who picked up the victims at the Lake Moondarra caravan park on the morning of October 5, 1978,” Hughes read from the earlier findings.

“He probably shot them to death on the same date.”

While the court has accepted the original finding, O’Connell will also take into account new material gathered by cold case detectives.

Edwards’ brother said they had not given up hope of finally finding answers.

“We are satisfied with the investigation by the cold case detectives and are confident that the coroner will take that investigation into account,” Barry Edwards told AAP.

A $250,000 reward issued in 2019 remains in place. 

The inquest has been set down for nine days and will hear from up to 40 witnesses as it traces the trio’s outback journey and explores events at the Lake Moondarra caravan park.