Adelaide man Peter Rex Dansie has been sentenced to life in prison for the murder of his wife Helen, after he pushed her wheelchair into a pond and left her to drown.

The 71-year-old was found guilty of murder in December last year, by pushing his disabled wife, 67, into a pond in her wheelchair in Adelaide’s Veale Gardens in April 2017. During the trial, prosecutors alleged that Helen had become “a burden he [Peter] was no longer prepared to tolerate”.

Handing down the sentence at the Supreme Court of South Australia on Thursday, Justice David Lovell described the murder as “the ultimate act of domestic violence”, reports The Advertiser.

“Driven by selfish motives, you planned how you would kill your wife and then cover up your crime,” the judge said, according to the local news outlet.

“Yours was an evil and despicable act… Helen, your loving and devoted wife of over 40 years, had simply become a burden to you.

“That simple statement underscores the vicious and callous nature of your act… this was the chilling, premeditated murder of a person whose mistake was to trust you.”

Dansie – who has launched an appeal against the conviction and maintains his claim that Helen’s death was an accident caused by faulty brakes – will serve at least 25 years behind bars, meaning he will likely die in jail.

According to the judge, he had neglected his wife’s needs, before making the decision to end her life when she became a “burden” on his finances.

Mrs Dansie’s body was recovered from the 1.5 metre pond in Veale Gardens, part of Adelaide’s parklands, almost three years ago, however her husband has continuously denied any wrongdoing.

He is said to have jumped into the water in a bid to save his wife, after her wheelchair went into the water, and was being found “wet up to his neck” when police arrived at the scene.

Mr Dansie told police at the time that Helen’s wheelchair had been parked at the edge of the pond before it “surged” forward when its brakes were disengaged.