Timeline of how Sydney stabbing unfolded


* 2pm: Police receive calls about a man armed with a knife and wearing a balaclava wandering York Street in Sydney's CBD.

* Officers arrive to find a 41-year-old woman suffering a stab wound at the Hotel CBD on the corner of King and York Streets.

* A short time later, three members of the public detain the 21-year-old attacker, before he's arrested by police.

* 3.15pm: The body of a 21-year-old woman is found in a Clarence Street unit.

* Police investigate whether the body is linked to the earlier stabbing.

* 5.30pm: NSW Police Commissioner Mick Fuller confirms the two crimes are linked and reveals the alleged attacker - 21-year-old Mert Ney - has a history of mental health issues.

* Police say the Marayong man has no links to terrorist organisations but does have some "ideologies in relation to terrorism".

* Ney was allegedly carrying material "about other crimes of mass casualties and mass deaths around the world", the commissioner says.

* Detectives conduct a thorough search of Ney's western Sydney home.