Diego Carbone was in December found guilty of murder in a second trial, after his first conviction was overturned on appeal.
The judge-alone trial heard Carbone and an accomplice had lured 25-year-old Bradley Dillon into an underground car park in Leichhardt in August 2014, where he was stabbed repeatedly from behind and shot three times as he ran away.
The court had previously heard Mr Dillon had been chasing repayment of money his sister lent to an ex-boyfriend who was a member of the Saint Michael Fight Club.
Carbone and his accomplice and cousin Antonio Bagnato were current or former members of the boxing and martial arts club, and both knew Mr Dillon from school.
Bagnato had been Mr Dillon's friend, the court was told during the trial.
Bagnato fled the country soon after the killing, and Carbone twice tried to follow him overseas but was arrested by police at Sydney International Airport a few weeks later.
Addressing the court on Friday via video link ahead of the sentencing of Carbone, Mr Dillon's high school sweetheart and partner of 11 years Nadine said his death had left her "a dead woman breathing".
His attackers were "spineless cowards", Mr Dillon's sobbing mother said, noting all of her son's injuries were from behind.
After comforting the distressed woman, one of his sisters, Kellie Dillon, told the court her family had suffered through seven years of relentless waves of grief.
"When I first learned of Bradley's death, on that day, it felt like the waves were 100 feet tall and would crash over us without mercy ... all we could do was hang on.
"(Even now) the waves keep crashing ... on Bradley's birthday, Father's Day, Christmas lunch, milestones in his young children's lives.
"Everything is a constant reminder that he's missing and things will never be the same.
"The waves will keep on coming forever."
Carbone will be sentenced at a later date, with Supreme Court Justice Peter Garling now to consider how large a role Carbone played in planning and executing the murder.
"The Crown case ... is that the murder of Bradley Dillon was a savage and unprovoked killing, following a carefully planned and premeditated ambush of an unarmed men in circumstances where Mr Dillon had no opportunity to defend himself," prosecutor Michelle England said.
However, Carbone's lawyer has argued the decision to confront Mr Dillon was made shortly before the attack occurred, and that Carbone had no idea the man would end up dead.
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