Slain Sydney man Joe Antoun's final kiss

Miranda Forster

As Sydney debt collector Joseph Antoun lay dying in a pool of blood, his frantic partner Teagan Mullens struggled to roll him on his side.

"I remember hearing his last breath," Ms Mullens told the NSW Supreme Court on Thursday.

"I grabbed his face to kiss him.

"I remember the blood in his eyes and I felt his jaw crack in my hand - that will forever be our last kiss."

Ms Mullens wept as she described the impact of seeing her partner of eight years - her "soul mate" - gunned down in front of her on the evening of December 16, 2013.

"Joe was the love of my life, my soul mate and my best friend," she said.

"Everyone told us all the time that the love we shared was beautiful and rare.... How could somebody take that away from us?"

Mr Antoun was shot at least four times by a hired hitman when he answered the door of his Strathfield home in western Sydney.

Gang leader of the Blacktown Brothers 4 Life chapter Farhad Qaumi, 34, and his brother and second-in-command Mumtaz Qaumi, 32, have been convicted of murder over the killing.

In a judge-alone trial, they were found to have hired a hitman to carry out the shooting, after accepting a murder contract from Mr Antoun's former business partner Elias "Les" Elias.

Pasquale Barbaro, who was shot dead in Sydney last November, was also suspected to have been behind Mr Antoun's murder.

Thursday was the first day of a two-day hearing to sentence the duo and their 25-year-old brother Jamil over a string of violent gangland shootings in western Sydney in late 2013, and other offences.

Among them is the October 2013 shooting of Mahmoud Hamzy at Revesby Heights, over which the three brothers were found guilty of manslaughter.

However, only Mumtaz and Jamil Qaumi appeared in the dock at the Darlinghurst Supreme Court after Farhad chose not to attend.

His barrister John Stratton SC said the gang leader was concerned his "level of stress" might cause him to act in a way the judge might find "disrespectful to the court".

Both Farhad and Mumtaz Qaumi were no-shows in court in February when their guilty verdicts were handed down in Mr Antoun's case.

That time, Justice Peter Hamill was told the brothers were afraid they wouldn't be able to control their emotions.

Ms Mullens said she was disappointed the gang leader wasn't in court on Thursday.

"They'd like to say they're men but I think they're far from it," she said.

The hearing is due to finish on Friday.