Warning: This story contains distressing details and the last name of someone who has passed.

A woman who killed her cousin during an argument in a public park in Kununurra has been sentenced to eight and a half years in prison.

In July, 2023, Maryanne Undalghumen stabbed her cousin with a broken bottle, severing her jugular vein, while intoxicated.

She then sat with her cousin, Ms Unghango, cradling her in her arms until police arrived.

Ms Undalghumen, who is now 37, revealed the wound to police and admitted she had caused it.

Ms Unghango died at the scene despite attempts to save her, and Ms Undalghumen was arrested.

The ABC reports that Ms Undalghumen admitted to wanting to stab the victim during a police interview the day after the attack, but the interview was ruled inadmissible by Justice Natalie Whitby, who found police continued to question her, despite Ms Undalghumen clearly expressing she did not want to be interviewed.

Over the course of a five-day trial late last year, in Kununurra's Supreme Court in the far north of Western Australia the jury heard from witnesses, many of whom were related to both the accused and the victim, saw security camera and police body-worn camera footage, and was presented with DNA evidence.

On 20 November 2024, Ms Undalghumen was found guilty of manslaughter after the jury deliberated for several hours.

The ABC reports she was also found guilty of the unlawful wounding of a second woman, also a relative, who she struck in the head with the same bottle after she attacked her cousin.

The total prison term of eight years and six months in prison is backdated to Ms Undalghumen's arrest in 2023.

Justice Whitby said Ms Undalghumen's previous convictions for unlawful wounding, some against other family members and always under the influence of alcohol, indicated a high risk of future violent offending, the ABC reports.

"Your risk of reoffending in a violent manner is very high unless you can manage your alcohol abuse," she said.

Justice Whitby said other circumstances of aggravation included the fact Ms Unghango had been unarmed and there had been a small child present at the time.

The judge also identified mitigating factors, including Ms Undalghumen's traumatic childhood and her genuine remorse and sadness.

The sentence included a 20 per cent reduction because Ms Undalghumen had made an early offer to plead guilty to manslaughter, though that plea was rejected by the state which proceeded with a murder trial.

Ms Undalghumen could be released in January 2030.