An alleged double-murderer said he kept a pistol at his workshop in case he needed to scare someone, a witness in the Queensland trial has told jurors.

A witness in a Queensland double murder trial has told jurors the alleged killer told him he had once pulled a gun on two men who had stolen a vehicle from him.

Mechanic Brandon MacGowan, 43, is facing trial in the Supreme Court in Cairns for allegedly murdering Scott Maitland and Cindy Masonwells, whose bodies were found in scrubland near Cairns in 2012.

Prosecutors allege the motive was a dispute over $14,000 worth of restoration work MacGowan had agreed to carry out on their panel van.

It’s alleged he killed the Mount Isa couple after collecting them from Cairns airport on the night of July 5, 2012.

He denies the murder charges.

On Thursday, crown witness Rohan Davis told the court the couple flew to Cairns in April 2012 to collect their panel van, but were told by MacGowan it had been stolen from a Cairns street.

He said that in June that year MacGowan told him how he’d found the damaged van at a property south of Cairns and left a note for those who lived at the house.

“He told me when he got there there was no one there and he broke in … he could see the van in the shed,” he told the court.

Mr Davis said the accused told him the alleged thieves visited his workshop some time later.

“He said when they were there basically he got them in the door, he shut the door behind them and got a gun and got them to sit with their back up against the wall,” Mr Davis said.

He said MacGowan told him he pressed a .22 calibre pistol up against the head of one of the men.

MacGowan said he arranged with the men for the panel van to be returned and for them to pay for the damage, Mr Davis said.

He also claimed MacGowan told him he kept a pistol at his workshop “in case he ever needed to scare someone”.

After the evidence, Justice Jim Henry cautioned jurors against taking hearsay into account when determining a verdict.

Another crown witness, Paul Harris, told the court MacGowan had told him a similar story that involved the accused threatening the alleged van thieves when they came to his workshop.

“He said he pulled a gun on them,” he said.

“He said keep quiet. I’ll show you. He went into his office and showed me there was a gun.”

Forensic scientist Leanne Skerke testified that several blood stains and a pool of blood were found in a white van which prosecutors allege MacGowan had been driving when he collected Mr Maitland and Ms Masonwells from the airport on July 5, 2012.

She said a button, a camera memory card and a discharged cartridge case were found in the van.

Prosecutors have argued the panel van, which Mr Maitland and Ms Masonwells had travelled to Cairns to collect from MacGowan, was never stolen and MacGowan failed to carry out restoration work on the vehicle.

The jury trial continues.