Investigators are still searching for a motive or explanation for Joel Cauchi’s Saturday attack, during which the 40-year-old killed six people and injured many more at the Westfield Bondi Junction centre.

Queensland officers had multiple interactions with Cauchi, who had a long history of mental illness, over an extended period and were reviewing that information to help a major NSW coronial inquiry into the attack.

Queensland Police acting Commissioner Steve Gollschewski said the 40-year-old had “come under our noses because of his conduct and behaviour”, but no particular action had to be taken against him.

Cauchi killed five women in the attack at the shopping centre, in Sydney’s eastern suburbs, with a male security guard also killed.

He lived with mental illness, including schizophrenia, for decades before his move to Sydney, his family said.

“He wanted a girlfriend and he has no social skills and he was frustrated out of his brain,” his father Andrew Cauchi said.

Police were previously involved in an incident between Mr Cauchi and his son over the possession of knives, Mr Gollschewski confirmed.

“What happened there was parents being very appropriate and trying to protect their child,” he said.

“Police are not mental health experts, they have to deal with things that are presented to them and the threat to the community but at that time there was no threat to the community.”

Cauchi was shot dead by a police inspector after killing Dawn Singleton, 25, Jade Young, 47, Pikria Darchia, 55, Yixuan Cheng, 27, and 30-year-old Faraz Tahir, while Ashlee Good, 38, later died in hospital.

Another stabbing, in which a bishop and priest were attacked during a live-streamed church service in western Sydney on Monday night, has been declared an act of terror.

ASIO director-general Mike Burgess said the circumstances of the two events clearly differed.

“To call it a terrorist attack you need indications of, or information or evidence to suggest, actually, the motivation was religiously motivated or ideologically motivated … that was not the case (at Bondi Junction),” he said.

Police declined to go into detail when asked if Cauchi was motivated by a hatred of women – citing a lack of information.

Reports he had visited shopping centres in western Sydney at Parramatta and Penrith in the days before the attack would be examined, NSW Police Commissioner Karen Webb said.

The investigation was probing his movements in the days and weeks before the attack and examining his childhood to get a better understanding of what he was thinking.

“I’ve made it clear we may not ever get an answer but we will get a picture of his movements and what he’s been doing,” Ms Webb said.

Seven people, including the injured nine-month-old daughter of victim Dr Good, remained in hospital on Monday night, although the baby’s condition improved from critical to serious but stable.

Politicians and fellow officers praised the bravery of the police inspector who responded alone and shot Cauchi, as well as the actions of several shoppers who confronted him.

French construction worker Damien Guerot, who faced Cauchi with a bollard as he tried to move up an escalator, could stay in the country as long as he liked, Prime Minister Anthony Albanese said.

Floral tributes are being left at the shopping centre, where a permanent memorial is being considered.

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