As of 27 April 2016[update], four other men have been charged in relation to the shooting, among whom Raban Alou was convicted of terrorism offences in March 2018.

[5] Police are believed to have had intelligence of a potential attack on the Parramatta headquarters up to 12 months prior, although it was unknown if that was linked to the 2 October 2015 incident.

"[3] On 2 October 2015, a 15-year-old boy carried a S&W .38 revolver to the street outside NSW Police Headquarters at Parramatta, walking past an unarmed plainclothes female detective.

[7][8][9] Farhad Khalil Mohammad Jabar (25 January 2000 – 2 October 2015), an Iranian-born boy of Iraqi Kurdish background, was identified as the shooter.

He was not known to police, and just prior to the attack he had visited a local mosque, where he listened to a lecture by extremist Islamist group Hizb ut-Tahrir.

[10] A report by Peter Lloyd on PM argued that Jabar had visited Bukhari House, which promotes the views of Feiz Mohammad.

[23] In November 2015, the Four Corners TV program ran an episode entitled Plan of Attack: The making of a teenage terrorist which documented the chronology of related events prior to the Parramatta shooting.

[25] On 6 October 2015, police arrested another student of Arthur Phillip High School for allegedly posting offensive and threatening material on Facebook in support of the shooting.

[30] On 23 November 2018 Atai was found guilty of "... assisting and encouraging 15-year-old Farhad Jabar to shoot Mr Cheng"... "... and helping the boy's sister reach Islamic State in Syria."

[37] NSW Police Commissioner Andrew Scipione and Prime Minister Malcolm Turnbull said Jabar appears to have committed a politically motivated act of terrorism.

[38][8][9] Muslim community leader Dr Jamal Rifi put out a statement, saying, "The horrible attack in Parramatta is a cold blooded murder with no justification or excuses.

[43] A statement by the Australian Federal Police to the ABC's Media Watch program said that "emotive headlines" in sensationalised news reports can "help extremists amplify their deliberate strategy to incite fear and hate.