An Islamic State sympathiser has refused to stand for a judge who jailed him for at least 13 years over his role in the terror killing of NSW Police accountant Curtis Cheng.
Talal Alameddine supplied Raban Alou with a loaded gun then given to 15-year-old Farhad Jabar, who shot Mr Cheng as he left work at Parramatta Police Headquarters in 2015.
The 25-year-old refused to stand for Justice Peter Johnson on Friday when he was sentenced to a maximum 17 years and eight months in jail with a non-parole period of 13-and-a-half years.
The judge said Alameddine's behaviour in the dock confirmed his concerns about his fundamentalist beliefs.
Justice Johnson wasn't convinced Alameddine had good prospects for rehabilitation and warned he may face a continuing detention order requiring him to be locked up after his maximum sentence expires in 2033.
One of the Merrylands man's supporters stormed out of the NSW Supreme Court saying the judge's sentence was "not f***ing fair".
Justice Johnson praised Mr Cheng's widow, Selina, his daughter, Zilvia, and his son, Alpha - who were all in court - for their "fortitude and dignity".
Alameddine in October 2017 pleaded guilty to recklessly possessing a thing connected with a terrorist act and supplying a pistol. The maximum penalty for both offences is 30 years.
Jabar - also known as Farhad Mohammad - was killed in an exchange of gunfire with officers after shooting Mr Cheng in the back of the head on October 2 in 2015.
Earlier that afternoon, Alou handed the revolver over to Jabar at Parramatta Mosque and the teenager performed the Islamic State one-finger salute to CCTV cameras 20 minutes before committing the execution-style murder.
Officers later found a chilling suicide note in the schoolboy's blood-soaked robes, stating he had "come to put terror in your hearts".
"You all are being watched 24/7, while you are asleep, awake, planning," the letter read.
"Your nights will be turned into nightmares, your days into hell ... by the will of Allah."
The note reflected the "perverse and poisonous" motivations held by Farhad and Alou in carrying out religious-inspired violence for Islamic State, the judge said.
Alou was jailed for at least 33 years in March.
Justice Johnson said Jabar and Alou were radicalised extremist supporters of Islamic State, while Alameddine had at least some level of sympathy for the "fanatical" organisation.
The court heard in the months leading up to the killing, the former tradesman was seen dressed in traditional Islamic clothing and had grown a "black, bushy full beard".
The judge found Alameddine likely knew the gun would be immediately used in a violent attack but he couldn't determine whether he supplied it for free.
Four days after the killing, Alameddine was caught on CCTV outside his family home laughing with friends and brandishing a semi-automatic weapon, flouting a firearm prohibition order previously imposed on him.
Alpha Cheng said the sentence reflected a clear link between Alameddine's actions and the "tragic loss of a very dear man, father and husband".
"We try to stay as strong as possible," he told reporters outside court with his mother by his side.
Alameddine, who has a criminal history and displayed no remorse, received a 15 per cent sentence discount for his guilty plea, the judge said.