Leisl Smith, 23, was last seen alive on CCTV getting into a white ute at Tuggerah railway station on the NSW Central Coast in August 2012.
The vehicle belonged to her accused killer, James Church, who died by suicide 10 years later on the eve of a verdict being delivered in the NSW Supreme Court in July 2022.
Justice Elizabeth Fullerton, who presided over his judge-alone trial, had settled on her verdict and finalised her written reasons but had not yet handed them down.
When Church died, the verdict was sealed and the legal proceedings were terminated in accordance with the laws of abatement.
During an inquest into Ms Smith's disappearance in June, the lead detective on her case advocated for an exception to the laws in the instance a verdict had already been reached.
"I believe in our investigation. I know in my heart what the result was going to be in trial," Detective Sergeant Michael Jones told the NSW Coroner's Court.
"That decision would have helped (Ms Smith's family) to reconcile and move forward."
The finding could be handed down as part of an inquest instead of in a criminal court, he said.
Deputy State Coroner Harriet Grahame is set to hand down her findings about Ms Smith's disappearance on Monday, more than 13 years after she was last seen alive.
The inquest was told the 23-year-old had been in a relationship with Church, then aged 42, in the months before her disappearance.
She had been on the cusp of enacting her bright plans for the future, including going back to TAFE to study, her sister recalled.
"Leisl had a life full of possibilities and potential," Jerildene Cane said.
She said she had been "forever changed" by her sister's disappearance, which sparked 13 years of questions and an unwanted "rollercoaster of psychological highs and lows".
"I don't want another family going through what I have in any shape or form," Ms Cane said.
Ms Smith's body has never been found.
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