Six months’ pregnant with two children at home, a young regional Victorian woman was understandably upset when her four-year-old found a gun inside their couch.

Kiara Ferguson, 27, took the homemade firearm from the girl and marched to the back of the family home, where her partner of 10 years was in the toilet.

“What have I told you about this?” she said to Adam Winmar, the father of her children, a court has heard.

Ferguson dropped the loaded weapon – a homemade 12-gauge spring pipe gun – on to the tiled bathroom floor.

In what supreme court justice Michael Croucher said was “a stroke of terrible misfortune”, the gun hit the tiles and fired a single shot, which hit Ferguson below her eye.

“She fell to the floor, mortally wounded,” the judge said in a sentencing hearing in Shepparton on Friday.

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Winmar then called triple zero and began CPR, however Ferguson could not be saved. She died in the bathroom of their Shepparton home on 1 April 2023.

The court heard Winmar’s previous attempts to fire the gun had failed.

But Croucher said Winmar’s storage of the gun inside a crevice of their couch in the lounge room, which was easily accessible to their two children, had endangered their lives as well as Ferguson’s.

“It was a profoundly stupid thing to do,” he said, as he jailed Winmar.

“Any loaded gun is to be treated as potentially dangerous, especially so when young children might get their hands on it.”

Winmar was initially charged with a firearm offence and pleaded guilty in the Koori court, before prosecutors upgraded the charge to negligent manslaughter.

But the prosecution abandoned the most serious charge before a trial was due to begin. Winmar instead pleaded guilty to reckless conduct endangering life and possessing a firearm as a prohibited person.

The judge imposed a three-month prison sentence on Friday.

Prosecutor Jim Shaw had told the court that Winmar admitted to using methamphetamine every day and consuming GHB four to five days a week.

Winmar also had a lengthy criminal history and continued to offend after Ferguson’s death, including committing assault and choking offences, for which he was given a four-month jail term in April, the court heard. After completing this term, and while on a community corrections order, he committed an affray in public with others while holding a meat cleaver, for which he received another three months’ jail.

But Croucher ultimately found Winmar’s experience of losing his partner, not being allowed to see his children and his “extreme guilt and devastation” over what he did, were its own form of punishment.

“I am satisfied that Mr Winmar is extremely unlikely ever again to have a loaded gun at his premises, let alone to store a gun in such a manner,” the judge said.

Upon his release, Winmar must perform 200 hours of community work and undergo treatment for drug and alcohol abuse at a residential facility.

In Australia, the national family violence counselling service is on 1800 737 732. In the UK, call the national domestic abuse helpline on 0808 2000 247, or visit Women’s Aid. In the US, the domestic violence hotline is 1-800-799-SAFE (7233). Other international helplines may be found via www.befrienders.org.