The patched bikie gang member who shot and killed White Ribbon ambassador Karen Belej repeatedly lied to police about how she died, a court has heard.
Brandon Osborn, 37, appeared at the Supreme Court sitting at Mildura on Friday after pleading guilty in June to the manslaughter of his de facto partner at her home in nearby Cardross.
Osborn, a member of the Rebels Motorcycle Club, had previously faced a murder charge which was dropped after the plea deal.
Crown prosecutor Jeremy McWilliams said on the evening of May 1, 2016, Osborn held a gun close to Ms Belej's forehead and pulled the trigger after loading one round into the six barrel chamber of an unregistered revolver.
He said the evidence showed Osborn lied to police several times, including his claim the gun went off when Ms Belej grabbed for it.
Mr McWilliams said Osborn was "catastrophically reckless" when he deliberately pulled the trigger with the gun to Ms Belej's head.
He said Osborn was aware it was at the very least possible the gun may have discharged if he pulled the trigger.
But he said there wasn't enough evidence to prove beyond reasonable doubt Osborn had murderous intent.
The court heard Osborn was prohibited from holding a gun licence after an intervention order was taken out against him in 2014 by a previous partner.
Ms Belej's family and friends spoke about their grief and search for answers after her death, trying to comprehend that the White Ribbon advocate had herself become the victim of domestic violence.
In a victim impact statement her brother Chris Belej told the court getting justice for Karen was most important to the family.
He said he could not trust the word of her "cowardly killer" about her last moments.
The plea hearing continues.