The Sydney knife attacker who killed six people at an Australian shopping centre advertised himself online as a male escort and tried to join groups of gun owners.

Joel Cauchi, 40, from Queensland, had been known to police, particularly over the last five years, but had not been arrested or charged before he committed the attack on Saturday afternoon.

He was killed by a police officer during his knife rampage at the Westfield shopping centre at Bondi Junction in the east of Sydney.

In a post on a Facebook group in December 2020, Cauchi wrote: “I am looking for groups of people who shoot guns, including handguns, to meet up with, chat with and get to know.”

It has been reported that Cauchi had set up profiles on several male escort websites, including Australia Cracker, Empire Escorts and Escorts Australia.

Cauchi described himself in one profile as an “athletic good-looking 39-year-old” based in Sydney who was looking for a “fun time”.

In a photo posted on one escort site, he is pictured sitting on a chair wearing a Manchester United football shirt.

The owner of a knife-sharpening business in Queensland told Guardian Australia that Cauchi had asked about sharpening two “everyday knives” about three years ago.

The business owner said they thought the request was “weird” as “he wasn’t a chef or a butcher”.

They added: “He goes, ‘oh no, I just do a bit of dabbling in the backyard with the knives and I use them every day’.”

Cauchi also claimed to work as an English tutor, according to his Facebook page.

Days before the attack at the Westfield shopping centre at Bondi Junction in the east of Sydney, he posted on a Facebook surfing group: “I am surfing Bondi this afternoon if anyone wants to meet there for a surf!”

Cauchi grew up in Toowoomba in southern Queensland, according to his social media profile.

In a statement released through Queensland Police, the Cauchi family said: “We are absolutely devastated by the traumatic events that occurred in Sydney yesterday.

“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.”

Three women place flowers as a tribute near the crime scene at Bondi Junction in Sydney
Three women place flowers as a tribute near the crime scene at Bondi Junction in Sydney (Rick Rycroft/AP)

They added: “We are in contact with both the New South Wales Police Force and Queensland Police Service and 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.”

Queensland Police assistant commissioner Roger Lowe said Cauchi was diagnosed with a mental illness at the age of 17.

“From our investigations it would suggest that in the last number of years his mental health has declined,” he told a press conference.

He added that Cauchi, who he described as “itinerant”, had not been “prosecuted or arrested or charged for any offence within Queensland”.

Mr Lowe said the last interaction Cauchi had with Queensland Police was during a “street check” in December 2023 on the Gold Coast, adding he was believed to have subsequently moved to New South Wales and was sleeping rough or in a vehicle.

He said his family did “not have regular contact” with him, adding that Cauchi would “periodically text his mother with an update where he was”.