Peter Rex Dansie is on trial in the Supreme Court charged over the death of his wife, 66-year-old Helen, after her wheelchair toppled into a pond in the Adelaide parklands in 2017.

The couple's son, Grant Dansie, returned from overseas following his mother's death and agreed to "wear a wire" during a conversation with his father.

In the recording, played to the court on Monday, the younger Dansie can be heard repeatedly asking his father for details on how his mother died.

"I've been told pretty strongly not to comment," the 70-year-old said.

"I'm sorry I can't tell you more.

"Yesterday's paper is probably the best explanation."

The older Dansie, who was not under arrest at the time of the conversation, at one point told his son "the whole thing is a little bit shabby" and "I certainly haven't got much help from the police".

"Apparently it's a common way that the police here work that they try and be nice and get you on side then they twist what comes out into what they want," he said.

But prosecutors in the case have alleged it was "no accident" that Mrs Dansie's wheelchair ended up in the pond, and that her husband's story was implausible.

Earlier this week, the court heard Dansie told police he briefly climbed into the pond after she fell in but then got out to call triple zero.

He told an operator he tried to keep his wife's head above water and manoeuvre her to the edge of the pond but he was not able to rescue her.

Dansie, whose first trial was aborted earlier this year, has pleaded not guilty to one count of murder.

The trial continues before Justice David Lovell and without a jury.

Australian Associated Press