A "twisted and depraved" radicalised jihadist has smiled and given the Islamic State salute as he was jailed for 38 years over the murder of NSW police accountant Curtis Cheng.
Milad Atai refused to stand as he was sentenced on Friday in the NSW Supreme Court for helping arm 15-year-old Farhad Jabar who shot Mr Cheng in the head and then died in a shootout with police in October 2015.
Atai, 22, was also convicted for his instrumental role in getting Jabar's sister to IS-held territory in Syria and a later fundraising effort to help another person to Syria.
The father of one, who will be eligible for parole in 28-and-a-half years, smiled and stroked his beard after he learned of the sentence.
As he was led out of the courtroom, Atai raised his index finger in an IS salute, gesticulated towards the public gallery and the judge and shouted in a foreign language.
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"That itself is an indication of his current thinking, which is regrettable," Justice Peter Johnson said.
Justice Johnson said while Atai didn't supply Jabar with the murder weapon, he knew the plans and had supported the quest to supply the boy a gun.
Atai's best friend Raban Alou was jailed in March for 44 years for giving Jabar the firearm used in the shooting at the at NSW Police headquarters in Parramatta.
Weeks after the shooting, Atai appeared on ABC's 7.30 program as an anonymous IS supporter and was asked if he'd get himself "killed for Allah".
"I'm not gonna answer that, because if I say yes I'll get in trouble, and if I say no I'll be a liar," he replied in comments that weren't aired on the October 19, 2015, program.
In September this year, he expressed regret for the hurt he caused Mr Cheng's widow Selina.
But by October, he'd withdrawn the apology in letters written "in the name of Allah" that explained where he stood with the "remorse bulls***", how he was happy with his actions and that he'd "slipped up" by apologising.
"The approach adopted by (Atai) towards the Cheng family is cruel and devoid of basic humanity," Justice Johnson said.
Mr Cheng's son, Alpha Cheng told reporters Atai showed with actions in court and his own words that he was still "a tremendous risk to society".
"Nothing will take away the pain and the trauma which our family has been put through by these really twisted, depraved individuals," Alpha said outside court.
"Regardless of the sentence, I don't think this will give them the punishment that they deserve, but this is the justice system and we hope that justice has been served."
Atai, who gave evidence that he no longer supports IS but backs the Taliban, will be eligible for parole in September 2044.
