Bruce John Preston, 70, on Wednesday returned to testify at the two-week inquest into the 1978 murders of Karen Edwards, 23, Tim Thomson, 31, and Gordon Twaddle, 21, in outback Queensland.
The three friends were travelling on motorbikes on their way home to Melbourne for the Christmas holidays.
They were last seen alive at the Moondarra Caravan Park in Mount Isa on October 5 in the company of a man driving a brown and white Toyota LandCruiser.
The trio's decomposing bodies were discovered in bushland at nearby Spear Creek on October 24.
All three had been shot in the head and their motorbikes, camping equipment, gear and keys were missing.
For almost five decades, the crime has remained unsolved, but Queensland coroner David O'Connell has reopened the inquest in the search for answers.
Cold-case detectives charged Mr Preston with three counts of murder in 2019, only for the Crown to drop the circumstantial case in 2023.
For 47 years, Mr Preston has remained a person of interest in the investigation after being caught in possession of Mr Thomson's missing red BMW motorbike.
He claimed he bought the bike second-hand in Adelaide but had a forged receipt as proof of ownership and was later convicted of stealing the BMW.
No keys were found at the murder scene, with the victim's pockets turned out.
Mr Preston told the court the keys were in the BMW when he stole it.
"The keys are very important, because it would be foolish to suggest that these gentlemen left their keys in their motorcycles when they left the caravan park," counsel assisting John Aberdeen said.
"There was no personal property or belongings on any of these three people when they were found - it follows that whoever had those keys must have gotten them from Tim Thomson's body."
Mr Preston said he stood by his testimony that the keys were in the BMW when he took it.
The court heard Mr Preston had told officers he was riding Mr Thomson's bike on October 6 - 24 hours after the trio disappeared.
He only stopped and hid the vehicle when his father warned him to "put the bike away".
"I put it away after my father showed me a newspaper article (about the murders) ... He said to put the bike away, get the bike out of sight," Mr Preston said.
"I got scared - up until then, I thought I was just guilty of stealing a motorcycle.
"All of a sudden, this is bigger than I could ever imagine."
Mr Preston's father, now deceased, also admitted his son had borrowed the family's LandCruiser - similar to the vehicle seen at the caravan park when the trio disappeared.
He died convinced his son had committed the murders, the court was told.
"It's alleged that a vehicle looking very much like your father's vehicle entered Moondarra Caravan Park during the hours of darkness on October 5 and removed camping gear and the tents that had been left there by Karen, Tim and Gordon," Mr Aberdeen said.
Mr Preston could not recall borrowing the car that night and said LandCruisers were in "every second driveway".
"I can't deny taking the car, but I can't remember," he said.
However, he had no answer when told police traced only 20 vehicles matching the same colour, make and model in the mining town at the time of the murders.
Mr Preston has claimed privilege against self-incrimination and has been directed to give evidence by the coroner.
Throughout his testimony, the court has repeatedly questioned the veracity of his evidence, warning Mr Preston he was close to perjury.
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