A jury has been told that a devoted mother was "forced or coerced to write two letters" that said she was "leaving her husband and children for good" before she was allegedly killed 40 years ago.
John Bowie is accused of murdering his wife Roxlyn on or about June 5, 1982, when she was last seen alive at their home in Walgett, in north-west New South Wales.
The 72-year-old has maintained his innocence.
Ms Bowie's body has never been found.
Prosecutor Alex Morris has spent more than two days making his closing statement in a Supreme Court trial before Justice Dina Yehia that has spanned four weeks and heard from more than 60 witnesses.
The prosecution's argument is that at some point between 7pm and approximately 11pm on June 5, 1982, Mr Bowie killed his wife and at the very least hid her body.
In his closing statement Mr Morris told the court it was possible Mr Bowie "finalised the disposal of her body" between 7pm that night and when he left Walgett later that month.
He said Mr Bowie may have either fed his wife's body to pigs at a piggery he was familiar with or discarded her remains in a "bone pit" at the nearby kangaroo abattoir.
Mr Morris said the contents of the pit – typically the remains of skinned kangaroos – were set alight once every three weeks.
Claims letters part of 'performance'
Police statements tendered to the court detailed how the Bowies' neighbour, Ruth Ovens, described searching their house for Ms Bowie on the night she disappeared.
Ms Ovens had said she located a letter under a sugar bowl on the dining room table, which the court heard began: "Dear John, I'm leaving you and the kids for good".
Mr Morris told the jury the note "was in a glaringly obvious position" and claimed Ms Ovens found the note as part of "a staged performance by Mr Bowie" so that "an independent person would find it".
Three days after her disappearance, Ms Bowie's parents received a letter from their daughter that said she was leaving her husband and children.
The prosecution argued Mr Bowie could have dictated the letters to his wife, but it was "most likely he had her copy out what he'd pre-written for her to write".
Mr Morris revisited testimony from forensic document examiner Linda Morrell, who said the letters appeared to have been written slowly and deliberately, unlike other letters written by Ms Bowie which she had been given for comparison.
Ms Morrell said those letters were written "with speed and fluency".
He put to the jury that the accused placed a pre-written note in front of Ms Bowie to copy and that she was "copying his style".
The prosecution told the court that Mr Bowie travelled to Coonamble at some point to post his wife's letter to her parents.
'I hope I live to see my kids grown up'
In his closing statement Mr Morris told the jury that "given the history of violence" in Ms Bowie's relationship with her husband it was unlikely she would willingly leave her "beloved two children in the care of a violent man".
The Crown said Mr Bowie tended to be intentionally violent to women he was in domestic relationships with, including the alleged victim.
Mr Morris highlighted earlier testimony from Mr Bowie's now former partner Anne Bowie, who told the court she required surgery on her knee after he "picked her up off the bed and threw her across the room".
Mr Morris outlined statements from almost 20 witnesses praising Ms Bowie as a mother, claiming "her children were her life" and "never left her side".
The Crown said a letter sent from Ms Bowie to her mother three weeks before she disappeared gave "a direct window into Ms Bowie's thoughts, mind and her view of her children" at that time.
"I hope I live to see my kids grown up and have kids themselves, but then again I might not, because nobody knows what might happen," Ms Bowie wrote.
The Crown said it was powerful evidence of her strong maternal bond and the improbability that she just "walked away" three weeks later.
Defence slams police investigation
Defence barrister Winston Terracini SC began his closing address on Wednesday and will continue on Thursday.
He criticised police for not contacting relevant experts to establish important facts for details featured in the trial, including the state of Walgett's public transport system, flood records or whether pigs eat bones.
Mr Terracini told the jury the prosecution instead relied on witnesses' memories of events from 40 years ago.
He criticised the credibility of many prosecution witnesses and said there had been "an enormous number of witnesses who couldn't even remember what was in their police statements".
He pointed out a family was living in the backyard of the Bowies' home who "had heard the Bowies argue and yell before", but gave evidence they did not hear any noise on the night of the alleged murder.
