NSW Police Commissioner Andrew Scipione defended counter-terrorism raids across western Sydney, after three of four males arrested on suspicion of involvement in the murder of a police accountant were released without charge.
Raban Alou, 18, was still in custody on Thursday after dawn raids on Wednesday, in which hundreds of officers stormed several homes in response to the shooting of 58-year-old Curtis Cheng outside police headquarters in Parramatta.
Investigators will be able to detain him for another 100 hours after applying in court to increase the length of time he can be held in custody.
A 16-year-old, who cannot be named, was released on Wednesday night without charge.
Both teenagers were students at Arthur Phillip High School. along with 15-year-old Farhad Khalil Mohammad Jabar who shot and killed Mr Cheng last Friday.
Mustafa Dirani, 22, also a former student of the school, and Talal Alameddine, 22, were released earlier on Wednesday, also without charge.
The 16-year-old and a 17-year-old charged on Tuesday with assaulting police after allegedly supporting the killing were both in the same year as Jabar at Arthur Phillip High.
But Mr Scipione said on Thursday it would take considerable time to examine the evidence collected during Wednesday’s raids, and admitted it was frustrating for authorities.
“When we raid homes, the law’s quite clear: only when we have sufficient evidence that can put us in a position to charge an offender with an offence (and) put them before a court, that we can hold them,” Mr Scipione told 2GB radio.
“We’ve taken a lot of material during the course of these searches and that’s going to take us a long time to go through.”
Mr Scipione said the attack by Jabar was religiously motivated.
“This had a religious connotation to it, certainly,” he said.
“We know that this young man had been radicalised. We know that now.”
Police are now exploring how he came to be radicalised, and how he came to be in the possession of the .38 calibre revolver used in the attack.
Some of those arrested had attended the same Parramatta mosque where Jabar spent time last Friday before the fatal shooting, and at least three of the four were targeted last September as part of Operation Appleby, the nation’s largest counter-terrorism operation.
Justice Minister Michael Keenan said Australians should trust law enforcement agencies, pointing to the disruption of six attacks in the past 12 months.
Mr Keenan disputed allegations the police had “dropped the ball” in their monitoring of the situation.
NSW Police Deputy Commissioner Catherine Burn had said on Wednesday Jabar was not on the radar of counter-terrorism agencies, and “not somebody we would have assessed as a threat”.
“The most important thing is that anyone involved in this horrendous murder is held to account for their crime,” Mr Keenan told the Nine Network.