Cecilia Haddad asked her ex-boyfriend to leave her house. When he tried to 'shut her up' he killed her.

Content warning: This story includes deals with domestic violence and may be distressing to some readers. 

Days before she died, Cecilia Haddad gave her boyfriend an ultimatum. 

In April 2018, the 38-year-old asked Brazilian engineer Mario Marcelo Santoro to leave her Sydney apartment or else she would call the police, Australian detective John Edwards said, according to O Globo newspaper.

Her body was later found in the Lane Cove River in Sydney, a few kilometres from her apartment.

Five years on, Santoro has been sentenced to 27 years in prison in a federal court in Rio de Janeiro after he confessed to her murder this week.  

Now in his mid-40s, Santoro was convicted of aggravated homicide, asphyxiation, femicide and concealment of a corpse. 

A seven-person jury – made of six women and one man – delivered its decision on Thursday morning.

Santoro's lawyer said he will appeal.

Mobile phone tracking placed Santoro at Haddad's apartment and by the Lane Cove River where her body was later found, O Globo reported.

By then, Santoro had already left the country and flown back to Brazil.

Sand and vegetation from that same area was also found in the victim's car, which Santoro was seen driving in images caught by security cameras.

In testimony he delivered on Wednesday, Santoro acknowledged going to Haddad's house to retrieve his passport to catch his flight back to Brazil.

He said they got into a fight and he "grabbed her neck" and "squeezed really hard" before "she fell limp" in his arms.

"It was trying to make her shut her up, but unfortunately that's when the tragedy happened. I grabbed her neck and squeezed really hard. I didn't want to do that," said Santoro, according to the ABC.

Santoro, who otherwise appeared fairly relaxed during the trial's long and detailed testimonies, cried while confessing to Haddad's murder.

"The defendant only confessed in the jury room, after extensive evidentiary material had been produced against him," federal judge Ian Legay Vermelho said.

"In other words, he did not confess before the Australian police when he arrived in Brazil. He did not confess before the Brazilian investigators, nor before the judicial stages he had gone through up to that day."

Before the ruling, Haddad's mother, wearing a white T-shirt with a photo of her daughter, told reporters that Santoro was "not a human being but a monster" and that he belonged in jail.

- With AAP. 

If this has raised any issues for you, or if you just feel like you need to speak to someone, please call 1800 RESPECT (1800 737 732) – the national sexual assault, domestic and family violence counselling service. 

Feature Image: NSW Police/AAP.