Danny Zayat charged with murder over death of Tatiana Dokhotaru ...

Police have charged Tatiana Dokhotaru's estranged husband with her murder.

Key points:Police will allege in court Danny Zayat assaulted Tatiana Dokhotaru in her Liverpool unitMs Dokhotaru rang triple-0 at midnight on May 26 but police didn't find her body until around 8pm the next dayA critical incident investigation has been launched to assess the police response

The 34-year-old Canadian woman's body was found inside her Sydney apartment in May, 20 hours after making a triple-0 call.

Ms Dokhotaru made a frantic call for police from her Liverpool apartment just before midnight on May 26, telling them she was being assaulted by someone who was demanding money.

The phone went dead before the 34-year-old managed to give the operator the exact address and the call was categorised as "priority three" and officers did not attend her building for another three hours.

Tatiana Dokhotaru called police and said she was being assaulted.(Supplied)

The unit block had 297 apartments, and police databases had different addresses attached to Ms Dokhotaru's phone number, so they didn't find her until around 8pm on May 27 after a call from a concerned neighbour.

A critical incident investigation has been launched to assess the police response.

As part of NSW Police investigations into Ms Dokhotaru's death, detectives executed a search warrant at a St Clair home about 6am today and arrested 28-year-old Danny Zayat.

Danny Zayat was arrested this morning at a St Clair home.(Supplied)

He was taken to Penrith Police Station where he was charged with murder.

Bail has been refused and he is expected to appear in Penrith Local Court today.

Homicide Squad Commander Detective Superintendent Danny Doherty said police will allege that after the phone was thrown out of the unit Mr Zayat assaulted Ms Dokhotaru and she died.

"It's a vile crime ... no-one can stand for the fact that there's women being killed in their own unit," he said.

He described it was a "strong" circumstantial case and said detectives had been assisted by a "large number" of people in the community who had come forward with information.

He said they had also gathered important information about Ms Dokhotaru's life and associates during a trip to Canada last week.

"It really does demonstrate how seriously we take domestic violence in New South Wales," he said.

"One of the first calls we made today was to Tatiana's mother just explaining to her that someone has been charged with her murder. Her reaction was she was very happy with that outcome and thankful for the police."

Charge follows appeal for phone information

Last Tuesday police released CCTV vision which they allege shows Ms Dokhotaru's phone being thrown from her unit just moments after her call to triple-0 ended abruptly.

Police believe the iPhone 14 could hold critical evidence that would be vital to their investigation but have not been able to find it and worry it could be damaged.

The phone has still not been found, Detective Superintendent Doherty said.

They have urged anyone who may have found a phone in the vicinity of Norfolk and Bathurst streets at the time to come forward.

Detective Superintendent Doherty said last week that investigating officers considered the phone to be a "key part of the puzzle".

State Crime Command's Homicide Squad and Liverpool City Police Area Command established Strike Force Median to investigate Ms Dokhotaru's death.