A jury has been told how a woman witnessed four men kill her son with machetes and meat cleavers in their Sydney home three years ago.

Mohammed Karimi, John Khoury and Mahdi Mir have pleaded not guilty to the murder of Kesley Burgess, who was killed in his Lurnea home in 2010.

Prosecutors say they were part of a gang trying to steal "turf" off drug dealers in Sydney's south-west.

The men sat side by side in the NSW Supreme Court today as Ken McKay outlined the prosecution's case.

He said Karimi and Khoury recruited men for the attack while Mir was allegedly one of four men who carried out the killing.

The jury was told they armed themselves with machetes and meat cleavers and demanded cash and drugs.

The court heard Mr Burgess's mother Tracey Burgess watched them attack her son with the weapons as he lay on the ground.

She pleaded with the men to kill her instead, before running into the kitchen and finding some cannabis to give them.

Mr Burgess, 25, died in hospital two days later.

The family told police they did not know their attackers or why they had been targeted.

The jury has also heard from Maxine Rogers, who police say the group accidentally targeted in a home invasion at Warwick Farm on the same night.

She said her attackers - who prosecutors say are linked to the accused - held a knife to her throat in front of her daughters.