Could blood stains found in a missing man's bedroom be explained by a simple nose bleed?
Or are they the result of something much more sinister.
That's what presiding judge Justice Mark Ierace will soon have to determine as the trial of Kylie So for the murder of Elong Elong man Robert Dickie reaches its final weeks.
With no trace of Mr Dickie's body ever found, the Crown's case hinges on blood stain evidence to prove the 71-year-old retired mine worker is dead.
Taking to the witness box at the NSW Supreme Court in Dubbo, Senior Sergeant Scott Gane said a search of Mr Dickie's Wattle Road home in 2017 - 14 months after his disappearance - uncovered evidence of a "significant blood shedding event" in the bedroom.
Noticing areas of apparent bleaching on the off-white carpet in the bedroom, investigators pulled it up to reveal two "dark red stains" on the underside of the carpet, where the light coloured blotches had been.
A blue-light investigation also revealed evidence of blood on the mattress, bed frame, bed slats and three of the bedroom walls.
Sergeant Gane said tests of the stains came back positive for human blood.
Elsewhere in the house, investigators found two nail brushes with carpet fibres in their bristles and a bleach bottle which Sergeant Gane noted seemed to be "almost empty".
Complications of alcoholism, a possible explanation
Crown prosecutor Liam Shaw said the blood in the bedroom could be evidence of their theory that So killed Mr Dickie during a fight after he tried to kick her out of his home.
So had arrived in Elong Elong from New Zealand just days before Dickie disappeared.
Forensic pathologist Dr Allan Cala said the blood droplets found on the bedroom walls were in a "cast off" pattern, as if flung from a weapon as it was pulled back.
He said the amount of blood found in the room was "significant".
"It's felt medically that [losing] about 30 or 40 per cent of the blood volume of an individual ... without medical treatment ... can cause exsanguination or bleeding to death," he said.
However, defence counsel Ian Nash suggested there could be "innocent explanations" for the blood such as a nosebleed or blood being thrown up as a result of gastric ulcers caused by excessive drinking.
The court heard Mr Dickie drank five or six bourbons a day and binge drank regularly. Many empty bourbon bottles were found around Mr Dickie's home and property.
Dr Cala conceded he couldn't rule out these explanations but he found them to be "unlikely". He said nothing in Mr Dickie's medical records pointed to him losing that quantity of blood.
"They may be explanations for quantities of blood on the carpet but blood was found elsewhere such as on the walls," he said.
"What we would see [if someone sneezed with a nose bleed] is numerous tiny droplets of blood rather than single but small droplets of blood such as in this case."
The trial of Kylie So continues at the NSW Supreme Court in Dubbo on Tuesday.
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