Two boys, aged 14 and 16, were arrested on Wednesday morning in relation to the killing of Marco Tapia, 23, who was shot dead inside his family's Glen Alpine home, in Sydney's southwest, in the early hours of September 1.
The arrested teens were not present at the alleged murder but were part of a joint criminal enterprise through their actions, Detective Superintendent Joe Doueihi said.
Detectives suspect three other people committed the fatal home invasion.
'We will allege the boys were involved in a preparation plan and in the aftermath of the murders by disposing of vehicles, supplying weapons and cleaning the residence ... in exchange for financial payment," the homicide squad commander told reporters on Thursday.
The teens were identified early in their investigation and left a trail of evidence, he said.
"They were ... very clumsy in what they did," Det Supt Doueihi said.
"It wasn't very difficult for us to locate them. The 14-year-old offender, as he attempted to burn the kill car, burnt himself in the process and ended up in hospital."
Investigators were shocked such young, naive boys were targeted by organised crime, he added.
Police were also closing in on the main offenders, Det Supt Doueihi said.
NSW Premier Chris Minns said his thoughts were with Mr Tapia's family.
"I can only imagine having a son who's done absolutely nothing wrong, living his life and being murdered in his bed," he said following news of the arrests.
"The age of the people who have been accused of these offences is worrying for everybody."
Both teens were charged with murder, participating in a criminal group contributing to criminal activity, possessing an unauthorised prohibited firearm and two counts of taking a car without consent.
The younger of the two teens was also charged with damaging property by fire or explosion.
They were refused bail to appear at a children's court on Thursday.
Mr Tapia's parents, Sergio and Claudia, described the traumatic experience of witnessing their son's death during an interview with Nine's A Current Affair program on Monday.
Both were at home at the time of the shooting, along with their daughter.
"I remember him taking the last breath," Ms Tapia told the program.
"Hate came to our house."
Mr Tapia's death was Sydney's first of two suspected mistaken identity shootings in as many days.
Joshua Macdonald, 40, was shot dead at a Merrylands West home, in the city's west, about 3.15pm on September 2.
He had arrived at the home as a visitor minutes earlier, along with a second male and two children, who were inside at the time of the shooting.
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