A pregnant woman who stabbed a 22-year-old stranger to death after flying into a rage when her partner asked for a paternity test has been sentenced to a minimum of 16 years in jail.
Antoinette Aleisha Winmar, 31, was visiting her partner Joseph Cooper at Discovery Parks Swan Valley caravan park on August 16 last year when she became incensed by his suggestion the baby was not his.
The pair were living separately but Winmar was visiting him at the urging of her mother, with whom the court heard she also had a tumultuous relationship that featured frequent acts of violence.
They had been drinking alcohol and Winmar may have consumed 12 cans of a bourbon mix.
Winmar was also affected by methamphetamine and cannabis.
'Foul and abusive' language heard before stabbing
WA Supreme Court Justice Bruno Fiannaca recounted how neighbours heard "foul and abusive" language coming from Mr Cooper's unit, with one witness saying Ms Winmar sounded like she was "going crazy".
Ms Rose came out of her unit and spoke with Winmar.
The court heard another witness thought at first Winmar was happy to see Rose but then "turned" on her, punching her in the head.
"She continued to try to calm you down, standing on her verandah," Justice Fiannaca told Winmar.
Winmar then went to Mr Cooper's unit and found two steak knives.
"Mr Rose raised her hand in a defensive, non-threatening manner," Justice Fiannaca said.
'I am going to kill you'
Winmar screamed "I am going to get you, I am going to kill you", then stabbed Ms Rose in the chest, puncturing her lung and heart.
She then stabbed Mr Cooper in the back, leaving a one-centimetre wound before returning to his unit where she was found by police.
Ms Rose was given first aid at the scene, and stopped breathing at Midland hospital but was resuscitated, managing to cling to life for two days before she died.
Justice Fiannaca said Ms Rose's intervention was "well-intentioned" and it was a "tragic irony" that aspect of Ms Rose's character had cost her life.
He said the suddenness of the assault meant Ms Rose would have been taken by surprise and defenceless.
When police arrived, the court heard Winmar told one officer Ms Rose and Mr Cooper had "done it to themselves", but later pleaded guilty to Ms Rose's murder.
Victim was a 'beautiful, shining girl'
Justice Fiannaca made reference to witness statements from Ms Rose's sister and mother, who "missed Ms Rose constantly".
Justice Fiannaca read part of her mother's victim impact statement to the court in which she wrote: "Dusty was my beautiful, shining girl, she was grateful for everything in her life".
He outlined how her mother, Cheryl Francis, now has panic attacks and bouts of anger, screaming and crying.
The court heard how her older sister, Billie Rose, was frustrated and angry her sister lost her dreams for the future, and how her nephew missed his aunty.
Outside the court, Ms Rose's mother and friend remembered their loved one.
"Dusty was a strong, vibrant and talented life force," her mother and friend read in a combined statement.
"Her love for her family and her friends was unquestionable. She always went out of her way to help others, or just lend an ear.
"She was over the moon with her new nephew Jed [while] Dusty and her family were just getting over the loss of their father Steve.
"The impact of this evil, senseless act of violence, taking Dusty Rose away from the people who love her, has been devastating, heart-wrenching and has affected us all."
"There is genuinely no justification for this horrendous and senseless violent attack on someone who genuinely looked out for others. We will miss our angel in heaven forever."
In sentencing, Justice Fiannaca gave consideration to Winmar's cognitive impairments, which according to one neuro-psychological assessment included foetal alcohol syndrome disorder (FASD), attention deficit hyperactivity disorder (ADHD) and a learning disorder.
The report said these impairments placed her at greater risk of contact with the criminal justice system.
They also meant she would have poor judgement, difficulty learning from mistakes and that she would tend towards repetitive errors and immaturity.
Court hears of Winmar's troubled upbringing
Justice Fiannaca also gave consideration to her upbringing, which contributed to her "complex set of circumstances".
The court heard in her psychological assessments, Winmar painted a positive picture of her parents in her life, saying her mother was her best friend and her father wasn't violent, but Justice Fiannaca said that was inconsistent with the facts.
Born in Rockingham in 1990, Winmar's parents separated when she was two years old and neither of them worked.
Both parents abused drugs and alcohol — her father was a frequent methamphetamine user with an extensive criminal history.
Justice Fiannaca said her father was "an angry, violent drunk" who was "more than happy to visit his anger on women".
Winmar lived in state housing with her maternal grandmother from a very young age, moving frequently, but there was no evidence she was exposed to drugs while in her grandmother's care.
Parents' involvement was 'unpredictable and haphazard'
What records exist indicate her parent's involvement in her life was "unpredictable and haphazard" and whenever she was in their care, she was exposed to drug and alcohol use.
Their relationship was beset by violence, including assaults by and on her mother.
In one such incident in 2019, Winmar presented to a hospital emergency room saying her mother stabbed her after she threw a boomerang at her.
Another time, the court heard hospital records indicate she was stabbed by her mother with a shard of broken glass.
The court also heard she once grabbed her mother by the hair and threw her to the ground
By the age of 13, Winmar was sniffing glue, using cannabis and methamphetamine, before using benzodiazapenes and heroin later in life.
She gave birth to a son at the age of 16 and remained in a relationship with that boy's father despite it being marred by violence until he died of organ failure. The child is in the care of Winmar's mother.
Winmar to spend at least 16 years in jail
In delivering his sentence of life, with a non-parole period of 16 years, Justice Fiannaca said he had to weigh the mitigating factors of cognitive impairments and childhood deprivations, for which she was not responsible, with the risk she posed to the public and the need for general and personal deterrence.
He also noted her drug use, of which she chose to partake, had the potential to aggravate her conditions.
With time already served, Winmar will be eligible for parole in 2037.
The court heard Mr Cooper remains in a relationship with Winmar, and had brought her other son, whom she gave birth to in 2022, to visit her in jail.
