A Sydney woman who stabbed her cousin to death after a violent and prolonged argument over her new Mercedes was not acting in self-defence, a jury has been told.
CCTV footage captured arguments between the pair before Katherine Abdallah armed herself with two knives and stabbed Suzie Sarkis, prosecutor John Bowers said on Wednesday.
"The crown case is that Ms Abdallah stabbed Ms Sarkis as an act in a series of violent acts that were generated or triggered by ongoing hostility and aggression that Saturday because of the incident of the car," he told the NSW Supreme Court jury in his opening address.
Abdallah, 37, has pleaded not guilty to the manslaughter of Ms Sarkis, 21, who had been staying with her at her Brighton-Le-Sands townhouse when she was killed on February 9, 2013.
Mr Bowers contended the stabbing was not done in self-defence, but Abdallah's barrister, Gregory Stanton, told the jury the Crown had to show this was not the case.
The footage demonstrated that Abdallah's actions were "at all times in lawful response to the attacks made on her" by her cousin, attacks which were "unprovoked, hostile and to some degree relentless", Mr Stanton said.
On the night before the stabbing, Ms Sarkis took Abdallah's new Mercedes-Benz coupe and drove it at high speed and was pulled over by police, the prosecutor said.
Police reported this to Abdallah, before Ms Sarkis again took the car out on the Saturday without her cousin's permission.
Abdallah became "annoyed and angry" when told of this and "even more so after she found out on Saturday that she had taken it a second time", Mr Bowers said.
"The crown case is that that caused ongoing conflict between the two women".
In the afternoon, witnesses saw them fighting in the street, while CCTV footage - which did not record sound - from inside the townhouse showed them appearing to have a verbal argument before it got physical.
At one stage, Abdallah is seen slapping her cousin's face, making various gestures and pointing aggressively towards the front door, before Ms Sarkis smashes a vase on the floor, Mr Bowers said.
After Ms Sarkis kicks her cousin, the older woman used a four-pack of drink bottles to strike her and runs into the kitchen, arming herself with two knives from the knife block, he alleged.
The younger woman was stabbed once on the right-hand side of her chest.
The CCTV footage allegedly showed Abdallah cleaning the knives and replacing them in the block, as she told the triple-zero operator she was applying pressure to her cousin's wounds.
The trial is continuing before Justice Julia Lonergan.