The "bizarre" recordings before and after the murder included the couple's plans to have children, a court has been told.
Duc Nguyen, 45, was found guilty of murder by a Victorian Supreme Court jury in March over the fatal shooting of Brian Laidlaw, 55, in July 2022.
His girlfriend, Scarlett Curham, 23, pleaded guilty to manslaughter for entering into an agreement with Nguyen to shoot Mr Laidlaw.
The pair faced a pre-sentence hearing on Wednesday, where details of what prosecutors claimed was a planned killing were aired.
Curham had texted Mr Laidlaw on the morning of July 12 to arrange a drug deal for her friend, prosecutor Kristie Churchill told the court.
Nguyen and Curham borrowed an Audi from a friend and attached stolen number plates to it, before driving to Napier Street in Fitzroy.
About 4pm, Mr Laidlaw walked to the car, greeted Curham and got into the front passenger seat.
After a few minutes, Nguyen shot him in the back.
Mr Laidlaw got out and ran across Napier Street, but he collapsed.
Nguyen pointed the gun at Mr Laidlaw before driving off with Curham, leaving the 55-year-old man to die on the road.
When Nguyen was arrested over the killing, police found eight voice recordings on his phone.
Ms Churchill said the recordings showed their plan was to shoot Mr Laidlaw and they had discussions about how it would be executed.
"You're about to f***ing shoot someone," the prosecutor said Curham was heard saying in one of the recordings.
In another recording the couple discussed getting "a bit of revenge" to make Curham happy over a grievance she had with Mr Laidlaw.
She said the recordings included plans to lure Mr Laidlaw to the car and how they were going to do it in broad daylight.
"The plan is clear - to shoot," Ms Churchill said.
But Nguyen's defence barrister Amelia Beech said there was no specific evidence to prove the shooting was pre-planned.
She said it was chaotic and disorganised but the pair only wanted to confront Mr Laidlaw with the gun and did not intend to shoot him.
"It's bravado, it's big-noting, it's pretending to be a gangster essentially," Ms Beech said.
She said the recordings did not support a finding that there was a plan to shoot Mr Laidlaw, but Justice Christopher Beale said the jury had rejected this.
"Whilst there's some bizarre conversations about things completely unrelated, such as when they have children and what their children will think of certain things, it progresses steadily and it ultimately culminates in Mr Laidlaw being shot," the judge said.
The couple will be sentenced at a later date.
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