A Queensland man is on trial in the Supreme Court charged with murdering a couple in the state’s far north in 2012.

A Queensland mechanic murdered a couple after he failed to carry out $14,000 worth of repair work on their van, a court has heard.

Brandon MacGowan, 43, has pleaded not guilty to killing Mount Isa couple Scott Maitland and Cindy Masonwells in July 2012.

Crown prosecutor Todd Fuller gave his opening address at the Cairns Supreme Court trial on Monday.

He said the couple flew to Cairns from Mount Isa on July 5, 2012, and were met at the airport by MacGowan, who was to take them to their panel van that he’d agreed to restore some months earlier.

The crown alleges MacGowan had lied to the couple, who were both in their 30s, and had never carried out the work.

“Unbelievable it would seem that failing to restore that vehicle and the fact they had paid $14,000 for it appears to be the reason that lead to their deaths,” Mr Fuller said.

The couple never arrived at an engagement party they’d planned to attend on the next day and were reported missing by a friend five days later.

Their severely decomposed bodies were found in scrubland near Cairns about a week later.

Mr Fuller said crown evidence would show Mr Maitland died from a gunshot wound to the back of the head and Ms Masonwells “likely” died from multiple stab wounds.

“The violent nature of their deaths are evidence of what (MacGowan’s) intention was,” he said.

Mr Fuller told the jury of six men and six women Mr Maitland and Ms Masonwells’ blood was later found splattered throughout the white van MacGowan had allegedly been driving when he picked up the couple from the airport.

A bullet cartridge found in the van is similar to that which killed Mr Maitland and the front seat had been cut with a sharp object, the crown will allege.

A crown witness will testify he saw MacGowan with blood on his clothes and injuries to his hands on the night of July 5, 2012.

MacGowan told police Mr Maitland and Ms Masonwells left his workshop in their panel van on July 5, 2012, and had planned to drive back to Mount Isa.

Friends and family of the alleged victims sobbed throughout the first day of the trial, which is expected to take at least a week.