TRIAL BEGINS: Jason Errol Gerhardt has pleaded not guilty to murdering Craig Marshall at Coonarr on August 1, 2015.
TRIAL BEGINS: Jason Errol Gerhardt has pleaded not guilty to murdering Craig Marshall at Coonarr on August 1, 2015. Contributed

Ex pleads not guilty to murdering woman's new boyfriend

A JEALOUS ex-lover murdered his former partner's new man by fatally stabbing him in a premeditated attack, a jury has been told.

On day one of his trial in the Bundaberg Supreme Court, Jason Errol Gerhardt today pleaded not guilty to intentionally killing 44-year-old Craig Marshall in the early hours of August 1, 2015, at a rural Coonarr property.

The five-man, seven-woman jury heard that Gerhardt did not dispute that his actions led to the death of Mr Marshall, but did contest that he intentionally went to the property kill or cause grievous bodily harm to the victim.

The trial is expected to run for eight days with the Crown expected to call at least 26 witnesses, including Gerhardt's former partner Kristen Eastley and her two teenage sons, one of whom is expected to give evidence that he saw Gerhardt stab Mr Marshall in the back as he knelt on the ground.

Crown prosecutor Greg Cummings opened his case against Gerhardt by telling the jury an "unarmed" Mr Marshall was "literally stabbed to death".

"Once the fatal wounds were inflicted - there were two - Mr Marshall had but minutes to live," Mr Cummings said.

"This was not a fight of equals but an attack on Mr Marshall by Mr Gerhardt armed with a knife, and at all times Mr Marshall was unarmed.

"Mr Marshall was stabbed nine times ... two of them were fatal. The two fatal wounds, one was to the chest ... the other fatal wound was to his back."

Mr Cummings said the prosecution's case centred on Gerhardt's actions in the lead-up to the attack.

"This was not something that happened in the height of passion, rather it was premeditated attack," he said.

Jurors were told that Ms Eastley would give evidence that she had been in an on-again, off-again relationship with Gerhardt for 10 years, but it had ended in 2012 and she had only been in a relationship with Mr Marshall for a few weeks when Gerhardt turned up at Coonarr and accused Mr Marshall of "kissing his girl".

Mr Cummings said the prosecution's case was that, on the night in question, Gerhardt first visited a fishing shack on the Coonarr property, took a knife from a tackle box and then confronted and stabbed Mr Marshall.

Barrister Callan Cassidy is representing Gerhardt.

The trial, before Justice Roslyn Atkinson, continues.