A woman who allegedly killed her boyfriend with an axe inside their townhouse in Western Sydney had been assaulted by him a year earlier.
Naea Moli is accused of stabbing Geo Sione, 35, several times while he was watching a movie in the upstairs bedroom of their St Marys home on Sunday afternoon.
CCTV shows the 34-year-old having a cigarette outside the Sydney Street property before catching a taxi to St Marys Police Station, where she was charged with murder.
"She was quite calm, she was lucid, she provided the information and we responded accordingly," Detective Inspector Jason Pietruszka said.
Mr Sione's body was found lying on his bed in what police have described as a "horrific" scene.
"They had been together for 10 years, they emigrated from New Zealand and they are known to police," Detective Inspector Pietruszka said.
"This is a horrific incident, it shows what can happen at its worst regarding domestic violence — we encourage all victims of domestic violence to contact police."
Detectives have been gathering bags of evidence from the two-storey home, including an axe and blood-stained sheets.
Court documents allege police had recently taken out an apprehended violence order against Ms Moli on behalf of Mr Sione.
The ABC understands Mr Sione was convicted of assaulting his girlfriend about a year before she allegedly murdered him.
Tracey lives across the road and said her son was left extremely anxious after seeing emergency services flooding the area.
"Waking up and seeing the forensic van still there and police cars and news crews pulling up — it was like, 'Oh my god, this is so real'," she said.
"As a domestic violence survivor myself, it has left me shaken, shocked — it has hit really close to home.
"It's very very sad. It just makes you realise that in this day and age you just don't know what people's circumstances are, or what happens behind close doors."
Ms Moli chose not to apply for bail when she faced Penrith Court in a green tracksuit on Monday afternoon.
She remains behind bars and will face court again in November.
