Moments after telling a triple-zero operator she was being attacked, Sydney woman Tatiana Dokhotaru was allegedly fatally struck by her estranged husband in full view of a child.

Danny Zayat was arrested on Monday after a painstaking three-month police investigation into the high-profile alleged domestic-violence-related killing of the 34-year-old Canadian national .

Ms Dokhotaru was found dead in her unit at Liverpool in Sydney’s southwest on the evening of Saturday, May 27.

Zayat was found with her body and was later charged with 22 domestic violence-related offences, but it took until Monday for police to finish building what investigators described as a strong circumstantial case for murder.

The 28-year-old allegedly dealt the fatal blows shortly after Ms Dokhotaru’s triple-zero phone call was abruptly interrupted and her phone was tossed out a window late on May 26.

Homicide Squad Commander Danny Doherty said the killing was a “vile crime” and the circumstances surrounding the death were tragic.

“What makes it even more tragic and aggravating in the circumstances was (a child) was present at the time and remained in the unit for the entire time up until that following day when … located with Tatiana,” he said.

“It doesn’t get much worse than a woman being killed in her own unit in front of (a) child.”

The sequence of events means that police believe Ms Dokhotaru was already dead by the time officers responded to the initial triple-zero call and arrived at the apartment tower in the early hours of May 27.

An internal police investigation has been launched into that response after officers were unable to find which apartment in the Liverpool apartment tower the call had come from.

While Ms Dokhotaru’s phone has not been recovered, Detective Superintendent Doherty thanked the large number of people who provided other evidence that “buoyed” the months-long investigation.

Police also travelled to Canada to speak with her family, friends and associates.

One of the first calls investigators made on Monday morning was to Ms Dokhotaru’s mother to share the news her daughter’s alleged killer had been charged.

“She was very happy with that outcome and thankful for the police,” Det Supt Doherty said.

“We’ve been heavily involved with them over the last several months.”

Zayat appeared briefly in Penrith Local Court on Monday afternoon, sitting silently in the docks in a high-vis hoodie.

He made no application for bail.

The matter was adjourned to Campbelltown Local Court on September 27, when the St Clair man is also scheduled to appear on domestic violence charges related to Ms Dokhotaru.

A court in July heard the pair were in a relationship for five years, but in May 2022 Ms Dokhotaru took out an apprehended violence order against him.

Zayat’s lawyer previously told the Supreme Court the couple’s relationship was turbulent and toxic, but he said his client had been heard running through the hallway of the Liverpool block shouting “help me” around the time of Ms Dokhotaru’s death.

The 28-year-old also called triple zero and police observed him in extreme distress when they arrived at the scene, the lawyer said.

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