The 15-year-old who shot and killed a police worker in Sydney’s west on Friday has been named as Farhad Jabar Khalil Mohammad of Iraqi-Kurdish background and born in Iran, police sources have confirmed to Guardian Australia.

An increased security presence is expected at Sunday’s NRL grand final in Sydney after the “radicalised” teenager shot dead a police civilian.

Detectives are continuing to investigate the motive behind the fatal shooting of Curtis Cheng outside the state crime command in Parramatta.

Cheng had worked in the New South Wales police finance department for 17 years. He was shot from behind at close range by Farhad.

Police commissioner Andrew Scipione says investigators are still a long way from establishing a full picture of Farhad but “his actions were politically motivated and therefore linked to terrorism”.

Scipione says his investigators have no information to tie Jabar to a specific group.

He was shot dead as officers returned fire when he killed Cheng.

It is not clear whether Cheng was targeted because he came from the police building, but Scipione says the shot “was not an accident”.



“We believe that his actions were politically motivated and therefore linked to terrorism,” Scipione told reporters in Sydney on Saturday.



A strikeforce has been established to investigate.



NSW police chief Andrew Scipione and premier Mike Baird in Sydney on Saturday. Photograph: David Moir/EPA

Sources told the Guardian that initial checks by Australian counter terrorism officials suggested Farhad was not known to them, and was a so-called “clean skin” – not on the radar of those suspected to be inclined towards terrorism or to have been radicalised.

“There is nothing to suggest that he was doing anything but acting alone,” Scipione said.



One of the next steps in the investigation is to find out how the teenager got hold of the handgun.

Farhad’s family have spoken to police and are co-operating.



Scipione said police had no information to suggest the gunman posed “this type of threat”.

“We’re a long way from establishing a full picture of this man, his exact motivations still remain a mystery to us,” he said.

“We are exploring every avenue with regard to why he did what he did.”





The prime minister, Malcolm Turnbull, described the attack as a “shocking crime, it was a cold-blooded murder”.

“It is doubly shocking because it was perpetrated by a 15-year-old boy,” he said.



Turnbull said the Muslim community would be “shocked and appalled” by the killing and issued a warning against vilifying or shaming the community for the actions of “a very, very small percentage”.

He said the government could never guarantee attacks would not take place, but security agencies were working to prevent them and Australians must “go on and lead our lives”.

“We have challenges, terrorism is one of them. But they must never divert us from our commitment to being free Australians, working together to ensure we achieve our common goals,” he said.



The federal opposition leader, Bill Shorten, echoed Turnbull’s comments, reassuring Australians the country’s security and police agencies were among the best in the world.



“At times like this, it’s critical that we guard against dangerous division – we are stronger and safer when we stand together,” he said.



Mike Baird, the New South Wales premier, described the events as “chilling”.

“The shock of this event will be felt everywhere,” he told reporters on Saturday.



The NSW police minister, Troy Grant, said the circumstances surrounding the shooting made it “even more devastating”.

“This is a horrendous tragedy just days after we paid tribute to the men and women of the NSW Police Force for National Police Remembrance Day,” Grant said in a statement on Saturday.



