Former ambulance officer John Douglas Bowie has been found guilty of murdering his wife Roxlyn in rural NSW 40 years ago.
A NSW Supreme Court jury took less than five hours to reach its verdict on Monday afternoon soon after the five-week murder trial concluded.
In handing down the murder verdict, the jury was not required to consider an alternative charge of manslaughter brought against Bowie.
He has always denied being involved in the disappearance of his then 31-one-year old wife from their home in the northern NSW town of Walgett on or around June 5, 1982.
Mrs Bowie's body has never been found and she has not contacted anyone or been seen since.
While no method for the murder has been established, one possibility was that her body was disposed of by being fed to some pigs.
The jury was persuaded by the Crown's circumstantial case in which prosecutors alleged Bowie forced his wife to pen two letters saying she had left her husband and children, and then killed her afterwards.
Jurors heard she was a loving mother and that it was implausible she had simply left her family. The prosecution said she had not taken either of the two family cars and said travel from Walgett any other way would be difficult given the lack of public transport.
The Crown claimed Bowie's motivation for the murder was a desire to have an unfettered relationship with another woman Gail Clarke who was living in Sydney at the time. Ms Clarke has since died.
Admitting he was a known womaniser, Bowie's lawyers argued he would not have been so desperate to travel all the way to see Ms Clarke.
Evidence was also shown to the jury suggesting Bowie had a tendency of violence towards his domestic partners.
One witness who testified at trial claimed they saw someone with Bowie's description burying a bra and pantyhose in a gully at a golf course in Walgett.
Excavations of a property near the Bowie family home also uncovered a dress ring which the Crown claimed was owned by Mrs Bowie.
Prosecutors alleged Bowie made a number of admissions to the murder, including telling one woman he had "killed someone before" and separately told someone else that pigs left no trace of a body.
Bowie's counsel Winston Terracini SC rejected the prosecution case, saying there was no forensic evidence of a murder or even a struggle occurring at the couple's Walgett home.
The jury heard because Bowie was a violent man who drank heavily and womanised, his wife had ample reason to leave him voluntarily.
Mr Terracini said there were flaws in the police investigation and argued that the lengthy delay in bringing the criminal proceedings has caused some disadvantage.
Bowie will be sentenced at a later date.
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