A NSW man charged in relation to the shooting murder of police accountant Curtis Cheng told corrective services staff and firefighters he would "put a bullet" in every single one of them, a court has heard.

Raban Alou is facing a sentence hearing after pleading guilty to aiding, abetting, counselling or procuring a terrorist act by Farhad Jabar Khalil Mohammad, who fatally shot Mr Cheng outside NSW Police Headquarters in Parramatta in 2015.

Threats: Raban Alou.

Redacted crown documents previously alleged that Alou supplied 15-year-old Mohammad with a gun at a nearby mosque before the killing on October 2.

Crown prosecutor Paul McGuire SC on Monday told the NSW Supreme Court that Alou was lacking remorse, had extremist views and poor prospects of rehabilitation.