Screams heard on night of Sydney murder

The night Jessica Silva allegedly stabbed her estranged partner to death, her neighbour says there was a scream like she'd never heard before.

Silva has been accused of stabbing James Polkinghorne, 28, up to five times outside her family home in Marrickville in Sydney's inner west on Mother's Day in 2012.

The 24-year-old has pleaded not guilty to murder on the basis of self defence.

Neighbour Ngaoa Issaka-Joseph told Silva's NSW Supreme Court trial on Thursday she was inside watching television when the family heard someone screaming.

"I have never heard a scream like that before," she said.

Ms Issaka-Joseph went outside and saw three people in the middle of a road.

A "hysterical" Silva was holding the hand of her brother's girlfriend and repeatedly screaming, "Oh my baby", she said.

As Silva cried, her father Avalino Silva and brother Miguel restrained Mr Polkinghorne on the road.

"He was trying to get up," Ms Issaka-Joseph said.

Robyn James also told the court she and her husband Ian James were driving their daughter home that evening when they saw a body in the road.

"There was a lady and she was facing towards the road. She had an implement which I'm sure was a knife.

"Some gentlemen were holding her back ... they were yelling, they were dragging her back. She was pushing forward."

The trial has previously heard Silva had been verbally and physically abused by Mr Polkinghorne throughout their four-year relationship and had repeatedly told her friends she feared for her life as he was selling and consuming the drug "ice".

On the morning of Mr Polkinghorne's death he texted her: "I hope your mother gets poisoned by the flowers that you give her and you get gang raped".

"If you are alive (tomorrow) I'm caving your face," he later threatened.

But crown prosecutor Eric Balodis said: "There are lawful ways to respond to domestic violence. The crown's case is (the) accused response was not lawful".

The trial continues.