Katherine Abdallah told police her cousin was in 'serious trouble' day before death

Trial: Katherine Abdallah arrives at the King Street Supreme Court on Wednesday. Picture: Peter Rae
Trial: Katherine Abdallah arrives at the King Street Supreme Court on Wednesday. Picture: Peter Rae

"She's going to be in serious trouble when I get her."

That's what Katherine Abdallah told police at her Brighton-Le-Sands townhouse the night before she fatally stabbed her cousin, a NSW Supreme Court jury was told on Thursday.

Former senior constable Yasir Khan testified that the now 37-year-old then said: "You guys will probably be called back."

The officer was in fact called back the next evening, February 9, 2013, after Suzie Sarkis, 21, had been stabbed to death by Abdallah at the Brighton-Le-Sands home.

Abdallah has pleaded not guilty, on the grounds of self-defence, to the manslaughter of Ms Sarkis who had been staying with her at her Brighton-Le-Sands townhouse when she was killed.

The crown says that before the stabbing the cousins were involved in a violent and protracted argument about Ms Sarkis's use of Abdallah's new Mercedes which had been bought on lease for $184,000 on February 4.

Mr Khan told the jury he and other officers were doing speed checks on the night of February 8 when a black Mercedes was clocked doing 112km/h along the Princes Highway at Banksia.

The driver, Ms Sarkis, used her older sister Christine's name and said her cousin owned the car, which was slightly damaged when she hit the gutter when pulled over.

After she suddenly drove off, the officers went to Abdallah's address and told her of the incident.

She became frustrated and agitated, telling them the car was worth $200,000 and the tyres cost $4000, Mr Khan said.

"I bought that car on finance - do you know how expensive it is to replace parts?" Abdallah said.

When Abdallah rang her cousin to tell her to come home she got no answer. Mr Khan told her to let them know if Ms Sarkis returned.

As the officers began to walk away, Abdallah said: "She is going to be in serious trouble when I get her, you guys will probably get called back."

Mr Khan said he was on duty the next evening when he responded to a call about a 21-year--old woman being stabbed at a Brighton-Le-Sands townhouse.

He recognised her as being the female driver of the Mercedes.

The trial is continuing before Justice Julia Lonergan.

AAP