'To you, he's a monster but to me, he was a very sick boy': Joel Cauchi's father has spoken.

NSW Police are trying to piece together the motivation that saw a 40-year-old man attack nearly 20 people at a Sydney shopping centre on a Saturday afternoon.

Joel Cauchi from Queensland fatally stabbed six people and seriously wounded 12 others in a killing spree at Westfield Bondi Junction on April 13.

A man whose face we have chosen to blur to allow us to focus on the victims' legacy.

A man who had never been arrested or charged with a criminal offence. A man who mostly kept to himself, often sleeping in his car. A man who showed no signs of ideological motivations for the attack. But a man who appeared to be targeting women.

Read more: So this was an attack on women.

"This is so horrendous that I can't even explain it," Cauchi’s father Andrew said on Monday, as he tearfully apologised for his son's actions to media outside his Toowoomba home.

"To you, he's a monster but to me, he was a very sick boy."

In his parents' initial statement on Sunday, they said their son had "battled with mental health issues since he was a teenager".

Queensland Police confirmed Cauchi had been diagnosed with schizophrenia at age 17, during his final year at Harristown State High School.

Cauchi's mother, Michelle, said her son had lived at home until he was 35. They helped him graduate from the University of Southern Queensland and keep his mental illness under control.

"We are just ordinary people who brought up our son as best we could," his mother told reporters. "We did what we could for him."

His father said his son was doing so well, he was taken off medication; then he moved to Brisbane and began living an "itinerant" lifestyle, moving throughout the state before travelling to NSW last month.

Queensland Police have said he was single with no children and was unemployed when he moved to Sydney.

Cauchi had previously set up an online escort profile, where he described himself as an "athletic [and] good-looking guy" but did not feature explicit photographs of himself.

The 40-year-old moved from Queensland to Sydney in March 2024, renting a small storage unit in the inner city, where it is being reported he had been living.

Just six days before the attack, he notified a local Sydney Facebook group of his plans to go surfing at Bondi and asked whether anyone wanted to join him.

Image: Facebook.

Despite no criminal record, the police had been in contact with Cauchi on several occasions.

Queensland Police said they were last in contact with him in December when he was street-checked on the Gold Coast. While NSW Police said their only interaction with Cauchi was last year when they asked him to move along when rough sleeping at the Rocks in Sydney.

Police say CCTV footage shows Cauchi walked into Westfield Bondi Junction at 3.10pm, but left shortly after. He returned at about 3.20pm, and word spread among shoppers that a man was stabbing people.

Witnesses described the weapon as a 30-centimetre-long hunting knife to the Sydney Morning Herald. One man recalled a concerning interaction with him previously.

"[Cauchi was] a guy who liked his knives," he told the publication. "He wasn’t right."

In a post on Facebook 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.

His father, Andrew, said that when Cauchi briefly moved home to Toowoomba in January 2023, he brought various knives with him.

When he took the knives from his son, Cauchi called the police on his father. According to the ABC, he then drove and bought another one.

"I wish I knew what was in his bloody head," Andrew Cauchi said.

Cauchi's family found out about their son's actions and death — shot by the first police officer on the scene, Police Inspector Amy Scott — after recognising him in a green and gold Kangaroos' rugby league jersey.

"We are absolutely devastated by the traumatic events that occurred in Sydney yesterday," the family said in a statement issued on Sunday night by Queensland Police.

"Our thoughts and prayers are with the families and friends of the victims and those still undergoing treatment at this time.

"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."

"We are in contact with both the NSW Police Force and Queensland Police Service.

"[We] have no issues with the police officer who shot our son as she was only doing her job to protect others and we hope she is coping alright."

Bondi Junction on the evening of April 13. Image: Getty.

While his family knew Cauchi was living interstate, they did not have regular contact with him — with their last interaction being in March.

With five women killed and one man, police are now investigating whether the motive was gendered.

"It's obvious to me, it's obvious to detectives that seems to be an area of interest that the offender focused on women and avoided the men," NSW Police Commissioner Karen Webb saying on Monday.

"The videos speak for themselves, don't they?"

Cauchi's father — who acknowledged the victims were mostly women — said his son desperately wanted a girlfriend.

"He has no social skills, and he’s frustrated out of his brain," Andrew Cauchi said.

On Monday, NSW Premier Chris Minns told Sky News that a major coronial inquiry, bolstered by up to $18 million in extra funding, will examine Cauchi's "horrifying, vile act" as well as his previous interactions with authorities.

However, Minns said his motive might never be conclusively known.

"I'm so sorry about what my son has done. We don't know why he did what he did," his mother said.

More to come.

— with AAP.

Read more:

• The latest updates on the Bondi Junction Westfield attack.
• How to talk to children of every age about the Westfield Bondi Junction attacks, according to a grief counsellor.
• 'His actions were truly horrific': Joel Cauchi's family have released a statement about Saturday's attack.
• This feels very, very close. Because it is.
• The remarkable acts of bravery amidst the Westfield Bondi Junction attack.

Feature image: Facebook.