A man who allegedly went on a stabbing rampage through the streets of Sydney has been charged with a string of offences including murder.

Mert Ney, 20, allegedly killed Michaela Dunn, 24, in a Clarence Street apartment on Tuesday before allegedly stabbing Linda Bo, 41, outside a CBD hotel.

In a dramatic citizens’ arrest, three bystanders chased down the alleged killer as he ran through the city streets brandishing a bloodied kitchen knife.

The city workers pinned Ney down with a chair and a milkcrate and stood on his arms until police arrived.

Michaela Dunn has been remembered as a “beautiful young woman”.

He was arrested by police and taken to Royal Prince Alfred Hospital for treatment but was released and transferred to Surry Hills Police Station just after midday on Friday.

Ms Dunn was reportedly outspoken about violence towards women and online harassment, urging people to sign a petition, The Australian reports.

Police will allege Ney attended the Clarence Street unit for “the purposes of prostitution” before allegedly terrorising the Sydney CBD.

Detectives have collected evidence including footage of a man arriving at the apartment building at 1.30pm on Tuesday and leaving about 20 minutes later.

Ms Dunn was later found at the apartment with a laceration to her neck and was pronounced dead at the scene.

Investigators have been trying to piece together why Ney, who had a history of mental illness, launched the alleged attack.

On Friday night, Ney was charged with murder, attempted murder, wounding with intent to cause grievous bodily harm, intentionally choking with recklessness and common assault.

He is due to appear before Parramatta Bail Court on Saturday.

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-with AAP