'His actions were truly horrific': Joel Cauchi's family have released a statement about Saturday's attack.

The estranged parents of the knife-wielding man behind the Bondi Junction attacks on April 13 have "no issue" with the police officer who shot their son dead.

Queenslander Joel Cauchi, 40, stabbed six people to death and seriously wounded 12 others in a killing spree at Westfield Bondi Junction on Saturday afternoon.

He was shot dead by Inspector Amy Scott, with NSW Police later confirming there was no evidence to suggest his attack was driven by any motivation or ideology.

"At this stage it will appear related to the mental health of the individual," NSW Police Assistant Commissioner Anthony Cooke told reporters.

Cauchi's family issued a statement on Sunday afternoon, declaring they were absolutely devastated by the traumatic events and expressing their sorrow for the victims.

"Our thoughts and prayers are with the families and friends of the victims and those still undergoing treatment at this time," read a statement issued by Queensland police. 

"Joel's actions were truly horrific, and we are still trying to comprehend what has happened. 

"He has battled with mental health issues since he was a teenager."

They said they were in contact with NSW and Queensland police and had "no issues with the police officer who shot our son".

"She was only doing her job to protect others and we hope she is coping alright," the family said.

Cauchi moved to Sydney from Queensland in March and rented a small storage unit.

His family, with whom he only made periodic contact with, reached out to authorities after seeing his image on TV.

It is believed he was sleeping in a car and backpack hotels.

"Our understanding from speaking to the family (is) he has been an itinerant," Queensland Police Assistant Commissioner Roger Lowe said.

Queensland police have had no contact with Cauchi since December, when he was street-checked on the Gold Coast.

Mr Lowe said Queensland police had mostly been in contact with Cauchi in the past four to five years and indicated Cauchi's mental health had declined.

"The man has never been arrested by police in Queensland nor has he been charged with any criminal offence," he said.

Cauchi had no record of being subject to a domestic violence order, despite most of his victims being women.

CCTV footage in the hours before the attack showed Cauchi, wearing a black backpack, ordering a meal from a Vietnamese restaurant on Oxford Street.

Cauchi had previously set up an online escort profile, which did not feature any explicit images, that described himself as an "athletic good looking 39-year-old guy".

His now-deleted Facebook profile stated he grew up in Toowoomba and studied at Harristown State High School and the University of Southern Queensland.

In a post from his account to a Facebook group in December 2020, Cauchi was looking to meet up with "groups of people who shoot guns, including handguns". 

"Please send me a DM (direct message) if you can help me out! I live in Brisbane by the way," he wrote.

Cauchi's social media profile indicated he worked as an online English tutor and he notified another Facebook group of plans to go surfing at Bondi six days before the attack.

— with AAP.

Feature image: Facebook.