A woman charged with the stabbing murder of her cousin, who was also her flatmate, had argued with her about damage to a car the night before, a Sydney court has heard.

Prosecutors said victim Suzie Sarkis borrowed Katherine Abdallah's car two years ago and police had pulled her over for speeding.

She had also hit a gutter and damaged one of its wheels.

The Supreme Court heard Ms Sarkis was stabbed in the chest by Abdallah during an argument at their Brighton Le Sands home the following night and the entire incident was captured on CCTV cameras.

Police had stopped Ms Sarkis in a black AMG Mercedes and cautioned her, before going to Abdallah's home to speak to her about what had happened.

The officers said Abdallah was agitated and frustrated when she found out.

She told police the car was worth $200,000 and it would cost $2,000 to replace the damaged wheel.

Abdallah was heard by one of the officers to say Ms Sarkis would be in "serious trouble" and police would probably be called back to the home.

That same officer did return to the home the next evening to find Ms Sarkis being treated by paramedics for a stab wound to her chest.

Prosecution says CCTV cameras captured violent attack

The cousins had been seen in a violent confrontation on a nearby public street that afternoon.

Crown prosecutor Siobhan Herbert said later footage from inside the home showed Abdallah behaving angrily and aggressively towards Ms Sarkis.

The victim then picks up a vase and smashes it, before being intercepted by Abdallah as she tried to leave the unit.

Ms Herbert said Ms Sarkis can then be seen punching and kicking Abdallah repeatedly.

"Katherine Abdallah runs into the kitchen where she arms herself with two knives," said Ms Herbert.

The prosecutor said Abdallah "slashed at Suzie Sarkis a number of times and then stabbed her".

Defence barrister Gregory Stanton urged the jury not to pre-judge Abdallah.

"The law demands that she be regarded as an innocent person," he said.

He said the CCTV footage shows his client was subjected to an "unprovoked, aggressive, violent and prolonged" attack.

The trial is expected to last four weeks.