Prosecutors have argued Marcus Rappel should spend the rest of his life behind bars for killing Tara Costigan as she held their week-old daughter in her arms in "one of the most brutal murders imaginable".
The ACT Supreme Court heard Rappel's axe murder of Ms Costigan had been a "heinous, callous, pitiless slaughter of a loving, caring mother" – inside her home, in front of her three children, and all because she had tried to keep herself and her family safe.
Ms Costigan, 28, had taken out an interim domestic violence order against her ex-partner the previous day after she had grown concerned by his increasingly abusive behaviour towards her and her family.
Rappel pleaded guilty to the killing, breaching a protection order and two assaults on Ms Costigan's family members stemming from the domestic violence attack in Calwell last February.
Rappel had become fixated on the fact he wasn't present at their daughter's birth and still needed to pick up furniture from Ms Costigan's home.
Prosecutor Shane Drumgold on Thursday argued Rappel had decided to murder his ex-partner when he was served the order about three hours before the fatal attack.
Rappel, who later insisted he was joking, had said to his then-partner: "I did say I'd kill the next girl who took out an AVO against me."
He bought an axe and drove to Ms Costigan's house where he drove past 13 times in 46 minutes before he went inside.
Rappel chased Ms Costigan before he plunged the axe into her shoulder and then again into the back of her neck, severing her spine, as she fled with their baby cradled in her arms.
It emerged on Thursday he had then smashed the television Ms Costigan's sons, then aged nine and 11, were watching in the next room before he left.
Ms Costigan's teenage sister and her boyfriend were injured when they tried to stop Rappel and ripped the axe from his hands.
Mr Drumgold argued Rappel had gone back inside as they helped Ms Costigan to ask: "Is she dead?"
"We say he's not only not shown remorse, he's shown an absence of remorse," Mr Drumgold said.
"Here we are, one-and-a-half years after one of the most brutal murders imaginable and he's still trying to blame the victims and anyone else who'll stick."
Mr Drumgold told the court Rappel deserved the maximum sentence of life imprisonment for his crimes.
"Life sentences are reserved for the worst category of cases. It's extremely difficult, if not impossible, to conjure up a worse case of murder than this one."
Barrister Steven Whybrow, instructed by Ben Aulich and Associates, did not dispute the seriousness of Rappel's crimes and acknowledged they warranted a lengthy jail term. But he argued against a life sentence.
Mr Whybrow said Rappel's distress and tears shed in court had demonstrated genuine abhorrence, remorse and regret for his actions.
He noted Rappel disputed some of the facts surrounding the murder and had appeared "somewhat combative" under cross-examination, but said: "They are not sufficient circumstances to cause you to doubt he has genuine remorse and contrition for what he has done."
Mr Whybrow noted it was "a difficult factual case" with conflicting evidence and circumstances, but argued Rappel had not planned to murder his ex-partner that day.
He said all the evidence before the court indicated Rappel had been in a state of rage when he attacked.
"It's clear he was subject to a lot of emotional stress and distress."
Justice John Burns reserved his decision. He has not yet set a date for sentencing.