The Grand Mufti of Australia and other leaders from the muslim community are due to speak about the killing of NSW police accountant Curtis Cheng and subsequent raids, which led to the arrest of four people.
Raban Alou, 18, was still in custody yesterday after Wednesday's raids, in which 200 officers stormed several homes in response to the shooting the 58-year-old accountant outside police headquarters in Parramatta.
He can be held for another four days after investigators applied in court to increase the length of time he can be detained.
A 16-year-old, who can't be named, was released on Wednesday night without charge.
Both teenagers were students at Arthur Phillip High School, where radicalised 15-year-old killer Farhad Khalil Mohammad Jabar also attended.
Mustafa Dirani, 22, also a former student of the school, and Talal Alameddine, 22, were released earlier on Wednesday, also without charge.
A 17-year-old charged on Tuesday with assaulting police after allegedly supporting the killing in social media posts was in the same year as Jabar at Arthur Phillip High.
Some of those arrested had attended the same Parramatta mosque where Jabar spent time last Friday before the fatal shooting.
At least three of the four were targeted last September in the nation's largest counter-terrorism operation.
As well as examining how Jabar came to be radicalised, police are also investigating how he ended up with the .38 calibre revolver he used to kill Mr Cheng.
The Grand Mufti of Australia, Dr Ibrahim Abu Mohamed, is expected to speak to media this morning.
