Raelene Polymiadis, 65, is on trial in the South Australian Supreme Court, charged with murdering Brenda and Lynton Anderson.
Her parents were both aged 94 when they died in March 2022 and May 2023, respectively.
In her closing address on Tuesday, defence lawyer Marie Shaw KC told the jury that before Major Crime Detective John Olive interviewed Polymiadis on June 20, 2023, he had devised "a very clever plan".
"(It was) to ensure that someone (about to be) charged with double murder did not lawyer up and exercise their right to silence," she said.
Mrs Shaw quoted lyrics from the Men At Work song, Down Under, to make her point.
"One of the lyrics is, 'Can't you hear, can't you hear the thunder? You better run, you better take cover'," she said.
"My client didn't run, she didn't take cover.
"She went down to the police station on the basis that Det Olive told her that 'we're having a chat'."
Prosecutor Michael Foundas has previously told the jury that notes found in Polymiadis's car show "what she told police in that interview was planned and curated".
"Ms Polymiadis has written to herself 'sob here', and that corresponds with a point in the interview where (she) commences sobbing," he said.
But Mrs Shaw said her client had written 'sob breathe', in the context of when she was talking to her father and holding his hand.
"Not a script for an interview," she said.
"Someone who's in incredible grief, where she's trying to cope by making notes. Do you really think that that was a plan feigning on her emotions?"
Prosecutors have played two alleged confessions to God recorded in Polymiadis' car.
In one recording, she said: "I have sinned twice in my life, and I hate it, but I also know ... your blessing, Lord, that they did not want to go to a nursing home, that was their wish."
Mrs Shaw said the prayers should be viewed through the eyes of the Christian faith, and interpreted as Polymiadis accepting responsibility for her parents' deaths because her insulin played a part.
"You have sinned twice because the watchman at the tower failed to blow the trumpet," she said.
The court has heard Polymiadis, a type-1 diabetic with access to insulin, had been the last family member to see each parent before they became unwell.
Mrs Anderson died from an insulin overdose after being taken to the Flinders Medical Centre.
Mr Anderson also died there after he was found unconscious on his kitchen floor with a large amount of insulin in his body.
Prosecutors had not excluded the possibility that Mrs and Mr Anderson had made a choice to leave the world on their terms, Mrs Shaw said.
The trial continues.
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