Kingsley Alley Jr, 18, was found beaten and stabbed on a Palmerston driveway, just north of Darwin, on October 8, 2022.
Eight weeks earlier he had become a father.
Melissa Clancy, 39, her 20-year-old daughter Madison Butler, Dechlan Wurramarra, 22, and a teenager - who cannot be named for legal reasons - have pleaded not guilty to his murder.
Mr Alley's mother Chelsea Miller wiped tears from her cheek as prosecutors opened the month-long trial on Thursday.
Kingsley Alley Jr's mother Chelsea Miller (second from left) was among family attending the trial. ((A)manda Parkinson/AAP PHOTOS)
Crown prosecutor James Moore alleged Mr Alley's "tragic death" was an act of revenge after an altercation at a party earlier that night.
In CCTV footage shown to the court, Mr Alley is shown assaulting an Uber driver before yelling with Butler.
Butler believed Mr Alley had stolen her wallet and called her a 'slut', the jury was told.
The prosecutor also said that Mr Alley threw a drink on Butler.
"There was an incident at the end of the birthday gathering where the deceased behaved disrespectfully towards Ms Butler," Mr Moore said.
"That incident is important in the crown case, because that's where it started ... that explains why the four ... were angry at the deceased and why they wanted to get revenge."
Later that night, Butler and the three other co-accused drove around looking for Mr Alley before beating and stabbing him, causing fatal injuries, the prosecution alleged.
Each of the co-accused's lawyers disputed that Mr Alley's death was an act of revenge, instead asking the jury to "keep an open mind" until they heard all the evidence.
"I will be making forceful arguments about ... the presumption of innocence," Butler's defence counsel David Hallowes SC said.
"I'm not sure if any of you have been on a jury before ... but if you just stop for a moment and think about it, if any one of you or your family member, friends, loved ones were charged with a serious criminal offence, you'd want those principles to apply."
Clancy's defence counsel David Edwardson KC argued his client never got out of the car during the attack and remained several metres away when the fatal injuries occurred.
Up to 25 witness are expected to be called.
The trial continues.
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