Accused Sydney CBD stabber under guard in hospital

Mert Ney is expected to soon be charged over the Sydney CBD stabbing attacks.
Mert Ney is expected to soon be charged over the Sydney CBD stabbing attacks.

Investigators are yet to interview a man who allegedly slashed a woman to death and stabbed another during a terrifying rampage in Sydney's CBD.

Mert Ney, 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 Ney 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.

He 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.

"It is unclear when he will be deemed medically fit to speak with investigators."

NSW Police Commissioner Mick Fuller said it is hoped Ney will be released from 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.

Ney 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."

Australian Associated Press