How a grandfather consumed a fatal dose of the hard-to-come-by poison strychnine will remain a mystery after a coroner investigated his death.
Douglas Thrift, 71, was found unresponsive at his rural home in Denham, in the NSW Hunter region, on the afternoon of December 1, 2018 after he returned from playing a round of golf.
The "highly unusual" discovery of strychnine in his system at the time of death sparked a major police investigation.
That probe was unable to determine whether the poison was consumed willingly or administered by a third party.
An inquest in May probed factors including Mr Thrift's relationship with his wife and three sons, and his long-term struggles with alcohol.
Deputy State Coroner Carmel Forbes concluded it was not possible to determine the manner or circumstances of Mr Thrift's death beyond the cause being strychnine toxicity.
"The circumstance surrounding Mr Thrift's death and how he came to ingest strychnine remain unclear," she said in findings delivered on Wednesday.
Police were initially unable to locate the poison at his property and it was more than four years later that officers conducting a search under coronial orders found a dusty bottle of the toxin in a shed near his home.
Examination of the bottle found Mr Thrift's DNA on the mouth and rim, but attempts to obtain a viable fingerprint were unsuccessful.
"Given the bottle's proximity, the fact that strychnine is so otherwise unavailable and the fact that Mr Thrift's DNA is on the rim and mouth of the bottle, I am satisfied that on the balance of probabilities that this bottle is the source of the strychnine that (he) ingested," Ms Forbes said.
"The question remains did he intentionally take the strychnine to end his life."
The inquest was told Mr Thrift suffered from depression and had attempted to take his own life previously in 1984 and 2009.
Both of those incidents were believed to be related to his alcohol use and its effect on his relationships.
"This history is significant in the fact that in this prior attempt it was in the context of intoxication, a fear of losing his wife because of his drinking and it was impulsive," the coroner said.
In an interview with police, Ms Thrift told officers when her husband returned from playing golf she could "smell grog on him".
"I said something to him about drinking," she told investigators.
"He lent forward and held my face and said, 'I'm here for a good time, not a long time', then he went and laid down."
While it was possible Mr Thrift had taken his own life while under the influence of alcohol, the coroner said there were also a number of factors that did not support that conclusion.
These included that he had left no note or given any indication he was despondent and that he had made plans for the future, including purchasing $100,000 worth of farming equipment.
The coroner refrained from commenting about other ways Mr Thrift could have consumed the poison due to the possibility of new evidence coming to light in the future.
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