A 20-year-old Sydney man is expected to be released from hospital to police custody and face charges this afternoon.
State and federal police are undergoing an intensive search to determine whether alleged killer Mert Ney had possible links to terrorism, saying a fatal stabbing attack in Sydney's CBD was not yet considered terrorism-related.
NSW Police Force Commissioner Mick Fuller told media on Wednesday morning that an investigation into the motivation behind a stabbing rampage in Sydney could take weeks or even months and local authorities would be open to liaising with international agencies.
Mert Ney, 20, is under police guard in hospital and is expected to be charged with offences related to the stabbing death of a 24-year-old woman and the injury of a second woman in her 40s.
“What he has on social media, what we can find in his bedroom may shine a light… on what his intent was,” he said.
Mr Fuller described a USB allegedly found on the suspect after the incident, which the police claim was filled with footage of attacks in New Zealand and the United States as concerning.
“If we can link him to terrorist activities, the offences would see him locked away for a very, very long time.”
Police say the 24-year-old woman who was found dead in a Clarence St apartment was known to the primary suspect and they had been in contact by phone.
Police are yet to identify her or determine the reason the two were in contact.
Family member says she 'can't believe' it
A family member of Mr Ney said she couldn't believe what had happened on Tuesday.
"I’m just really sorry towards the victim and I don’t know how many people he tried to attack either, I’m also really sorry, and the 41-year-old I’m just really sorry to her family friends everything," she said.
"I wish there was a way I could make it better for her but I can’t. I can’t make it better for anyone else I wish I could I just want to say sorry to the family, sorry a million times sorry for everything we didn’t know he would do this.
"He’s never been violent in the past but this just hearing about it people were giving me so much support I didn’t know what was going on either with all this."
'Known to authorities'
The 20-year-old was allegedly on authorities’ radar after being declared missing by his family after a domestic violence incident, and police said that he’d been homeless for some time.
A search warrant has been issued for two premises in Sydney’s west and police said there will likely be search warrants issued for more locations.
“We need to backtrack his history, not just for past 48 hours but potentially two years,” Mr Fuller said.
The NSW Police Commissioner described the suspect's criminal history as "unremarkable", noting that he had been processed in the criminal system already.
“His history is not remarkable; he has low-level issues around theft … domestic violence linked to his family. If you look at his spreadsheet from a criminal history perspective it remains unremarkable. “
NSW Police Minister David Elliott said State and Federal resources will be dedicated to the case.
Appeal for witnesses
Hundreds of witnesses are believed to have seen the incident unfold between Clarence St and Wynyard St on Tuesday afternoon. Police will be conducting interviews of bystanders and people they describe as heroes, who “undoubtedly prevented the killing of more people.”
Mr Fuller appealed for anyone who may have witnessed anything or is aware of any changes in Ney’s demeanour or personality, to come forward.
“If a person has seen him… go to any place of worship please come forward,” he said.
Police believe the suspect self-admitted to a mental health facility in recent days but said that this element of the investigation was not a priority.
“They’re a criminal first, and the issue around mental health is a distant second”.
Suspect yet to be charged
The suspect, 20, remains under police guard in hospital after being arrested near Wynyard station on Tuesday afternoon.
He was detained by several members of the public who gave chase after he was seen wandering the streets and jumping on a car brandishing a bloodied knife.
Police believe he had earlier been at a unit for an appointment on Clarence Street, where the body of a 24-year-old woman was later discovered.
She had a laceration to her neck and was pronounced dead at the scene.
The 20-year-old was captured on CCTV arriving at the building at 1.30pm and leaving about 20 minutes later.
It's alleged he then went on to stab a 41-year-old woman in the shoulder at Hotel CBD and threatened to stab others before being restrained by bystanders.
The NSW Police Force commissioner said she was lucky to be alive, describing it as a miracle.
The suspect remains at Royal Prince Alfred Hospital, where he underwent surgery for a cut to his knee.
"He remains under police guard and is continuing to undergo treatment," NSW Police said in a statement.
NSW Police Commissioner Mick Fuller said it is hoped the man will be released from the hospital on Wednesday afternoon.
He is expected to be charged with murder as well as serious assault, among other possible offences.
Mr Fuller confirmed the rampage was not currently classed as a terrorist incident and that the "lone actor" had no links to terrorist organisations.
Police allege he did, however, have "some ideologies in relation to terrorism" - notably, a USB stick with information about mass deaths in New Zealand and the United States.
He had a history of mental health issues but his motive remains unclear.
"What is important from our perspective is really looking at his history on Facebook and other sorts of forums to see, was he in chat rooms? Does he have information on his computer - a manifesto in a sense? Is there some evidence that can link him to terrorism so we can essentially throw the book at him," Mr Fuller told 2GB on Wednesday.
"If we establish that he had terrorism as a motive and we can prove that, then I will certainly turn that on because that opens up a whole range of other criminal charges that would see him behind bars for a long long time."
Investigators are still searching properties in Blacktown and Marayong, in Sydney's west, for evidence.
They will return to the CBD for another canvass of the area.
Mr Fuller again praised the members of the public who helped restrain the 20-year-old using a milk crate and chairs.
He labelled them the "highest order heroes".
"There was a number of people that were distracting him and they saved lives," the commissioner said.
"They are true heroes."