Raban Alou has been sentenced to 44 years behind bars for obtaining a revolver and handing it to Farhad Jabar Khalil Mohammad, who then used it to shoot dead police accountant Curtis Cheng.

And after the sentence was given on Thursday morning, Alou stood to be led away by corrective services staff and made an Islamic State salute towards the back of the courtroom as he said "this is the beginning" and spoke in Arabic.

Mohammad, 15, walked closely behind Mr Cheng as the father of two left police headquarters in Parramatta on October 2, 2015. The teenager shot him in the head, killing him instantly, before he was shot dead by special constables.

The gun had been given to him that afternoon at Parramatta Mosque by Raban Alou, then 18, who had become increasingly radicalised and obsessed with the "poisonous and criminal views" of the terror group Islamic State.