A crown witness in a double murder trial in Cairns has told how he went back to playing video games after seeing a man drag a screaming woman from a van.

A witness in a Queensland murder trial has admitted turning up the volume on his video game to drown out the sound of a woman screaming.

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 Wednesday, the third day of the trial, crown witness Brendon Lubbers-Mott told the court that on the night of July 5, 2012, he heard a vehicle pull up outside the workshop where he lived in Cairns.

“When we went outside and had a look I saw a man pulling a girl out of the van by her arm,” he said.

The woman was screaming and told the man to “f*** off”, he said, but the man identified himself to Mr Lubbers-Mott as “Brando” and told him to “stay out of it”.

He said he went back inside the workshop and resumed playing his Xbox.

“I heard a bit more screaming so I turned up the TV a bit more,” the 21-year-old said.

After being questioned by defence lawyer Josh Trevino, Mr Lubbers-Mott told the court he hadn’t told detectives in 2012 that the man had identified himself as “Brando” and that it was too dark to get a good look at him.

Also on Wednesday forensic pathologist Paull Botterill, who carried out autopsies on the bodies which were discovered in mid-July 2012, told the court Mr Maitland died from a single gunshot wound to the back of the head.

The damage would have been “irreversible and catastrophic” and the 35-year-old would have become unresponsive immediately and died within four minutes, he said.

Dr Botterill, who works for Queensland Health, said the level of decay was such that he couldn’t rule out other injuries.

He said Ms Masonwells, 33, died from a stab wound to the chest although it’s possible she was stabbed multiple times as her shirt had a number of tears.

Moderate to severe force would have been used to create the wound as it passed through bone, he testified.

Another Crown witness, Brett Luffman, said MacGowan had told him on July 9, 2012, he’d had to “sort a couple of people out”, but admitted he hadn’t told detectives about the conversation when he was interviewed in 2012.

Another Crown witness, lawyer Jennifer Cutler, said there was “no animosity” when she met with MacGowan, Mr Maitland and Ms Masonwells in April 2012 to draw up a deed agreement in relation to payment for the panel van.

The jury trial continues.