A Samoan father-of-five, consumed by ‘morbid jealousy’ over an unfounded suspicion that his wife was having an affair with his brother, savagely stabbed her to death in a frenzied knife attack.

Rimoni Muliaga, 44, repeatedly plunged a large kitchen knife into Lise Muliaga, 37, in the garden of his brother’s bungalow in Melton South, on the outskirts of Melbourne, on 18 September 2023, just weeks after the family had relocated from New Zealand.

Three of their young children, aged 12, seven and five, bore witness to the horrific assault and its shocking aftermath.

Ensure our latest news headlines always appear at the top of your Google Search by making us a Preferred Source. Click here to activate or add us as Preferred Source in your Google search settings.

On Wednesday, Supreme Court of Victoria Justice James Gorton condemned Muliaga for the murder.

“You stabbed your wife, Lise, multiple times with a kitchen knife. You did so in front of your children in the backyard of your brother’s house,’ he addressed Muliaga.

“You stabbed her because you mistakenly believed that she was having an affair with your brother.”

The judge described the killing as ‘an act of the most serious domestic violence against an innocent and unarmed woman’ that ‘warrants serious condemnation’.

Muliaga had quarrelled with his wife that morning after accusing her of the affair – a suspicion he had harboured for some time despite it being entirely without foundation.

Following her return from a stroll, the dispute escalated in the bungalow where three of their children were present.

The court was told that Muliaga assaulted his wife with a knife, stabbing her four times – twice in the right shoulder, once in the left upper chest and once in the left breast.

The lethal injury was a 9.5cm stab to the upper chest that sliced through two ribs, severed two major blood vessels, resulted in substantial blood loss, punctured the chest cavity and damaged a lung.

Mrs Muliaga had battled for her life, sustaining defensive knife wounds to her arms as she desperately tried to ward him off.

“It was a frightening and violent death,” stated Justice Gorton.

The court heard how one of the couple’s young daughters ran screaming to the main house.

When family members hurried to the backyard, they found Mrs Muliaga seated on the ground, the knife still lodged in her shoulder, bleeding heavily.

Muliaga was observed standing over her.

His sister-in-law yelled at him, questioning his actions.

The murderer fled up the street but later claimed: ‘Lise and (his brother) were sleeping together.’

Muliaga’s brother dialled triple zero and performed CPR, but despite briefly reviving a heartbeat, Mrs Muliaga was pronounced dead at 2.33pm.

Muliaga was apprehended nearby, his hands still stained with blood.

The court was informed that he repeatedly requested his ‘mental health medication’ from police and stated he hadn’t taken it since the previous day.

Justice Gorton noted Muliaga seemed genuinely shocked and distraught upon learning of his wife’s death, even requesting to telephone her. A jury found Muliaga guilty of murder in December after a trial during which he admitted the stabbing but contested his intentions.

Justice Gorton sentenced Muliaga on the understanding that he stabbed his wife with the aim of ‘causing really serious injury’, without regard for whether she survived or perished.

The judge noted the assault was spontaneous, not planned, yet entirely unprovoked.

The reality that three children witnessed their mother’s brutal death was an aggravating circumstance that heightened the objective severity of the offence, Justice Gorton stated.

The court learnt Muliaga was born in Samoa in 1981, one of nine siblings, and endured a troubled childhood involving physical abuse.

The court heard Muliaga possessed a low IQ of merely 61, placing him in the lowest 0.5 per cent of the population and meeting the threshold for intellectual disability, along with impaired executive functioning and inflexible thinking.

He had a history of mental health difficulties, including depression with psychotic features and a prior diagnosis of schizophrenia in New Zealand.

A forensic psychiatrist who assessed Muliaga concluded he suffered from a major depressive disorder rather than schizophrenia.

Whilst the court determined the condition reduced his moral culpability, Justice Gorton stressed it did not absolve the crime. Muliaga understood his actions were wrong, Justice Gorton stated. The court heard about Muliaga’s history of violent conduct towards Lise, including an occasion where his brother found him on top of her and another where his sister-in-law saw him with his hand around her neck.

Their children, now coping with the help of family, provided victim impact statements explaining they confronted life without their mother and the trauma of knowing their father killed her.

Muliaga, who is not an Australian citizen, is expected to face deportation upon release.

Justice Gorton handed Muliaga a 24-year prison sentence with a non-parole period of 18 years and six months.

He has already served 919 days in pre-sentence detention.