Tanya Hinrichsen, Gavin Scott Skinner and Robert John Thrupp stand trial for murder of Steven Hinrichsen

A disabled man was brutally stabbed to death because he was “an inconvenience” to his wife’s relationship with her new lover, a court has heard.

Gavin Scott Skinner, Tanya Hinrichsen and Robert John Thrupp are all accused of the murder of Steven Hinrichsen. Picture: Nine News

Steven Hinrichsen was stabbed to death in his own home by two other men – including his wife’s new boyfriend – because he was an “inconvenience and an impediment” to his wife’s new relationship, a jury has heard.

Mr Hinrichsen’s wife Tanya Hinrichsen, 43, her new lover Gavin Scott Skinner, 46, and Mr Skinner’s friend Robert John Thrupp, 47, are each standing trial in the Supreme Court after pleading not guilty to murdering Mr Hinrichsen, 63, in December 2018.

Opening the trial, Carmen Matteo, prosecuting, told the jury there was a “tense triangular relationship” between the Hinrichsens and Mr Skinner.

“A love affair between Tanya Hinrichsen and Gavin Skinner was so far advanced that (she) wore an engagement ring,” Ms Matteo said.

“They wanted to be together and desperately so.

“Steven Hinrichsen was killed for the simple and painfully obvious reason that he was in the way of Tanya Hinrichsen and Gavin Skinner’s wish to be together. He was an inconvenience and an impediment.”

Morphett Vale man Steven Hinrichsen was stabbed to death, and three people are standing trial accused of his murder.

She said Ms Hinrichsen and Mr Skinner went to Christies Beach Police Station about midnight on December 15, 2018, seeking advice on how she could leave the Morphett Vale home she had shared with her husband.

In the hours that followed, Ms Matteo told the jury the trio – and Mr Thrupp’s daughter – had gone to pack up some of Ms Hinrichsen’s belongings.

Hours later, prosecutors allege the two men returned and stabbed to death Mr Hinrichsen, who required a wheelchair and walker for mobility because he was recovering from two breaks in his right leg.

Mr Hinrichsen suffered numerous injuries including multiple stab wounds, two of which penetrated his chest into his lungs and the external wall of his heart. Such was the force of the attack, Ms Matteo said, Mr Hinrichsen’s bones were damaged and his scalp cut open.

Ms Matteo said Mr Hinrichsen’s killers did not need to force entry into the house and had “such venom for the man, they left a smashed photograph of him on top of his bleeding and mangled body”.

“It was angry and it was personal,” she said.

He was found face-down in a pool of blood the following morning when Ms Hinrichsen returned and called triple-0. Before police arrived minutes later, the jury heard she had sent two images of her dead husband to Mr Skinner alongside the words “Steven’s dead”.

The court head in the weeks before Mr Hinrichsen’s death, Mr Skinner had twice assaulted Mr Hinrichsen, while the couple had shared multiple text messages professing their love for one another.

Tanya Hinrichsen in 2018 ahead of an earlier court appearance. Picture: Nine News

She said many more text messages indicated an “exasperation and bitterness” towards Mr Hinrichsen, while on the day before the murder, Mr Skinner sent a text saying he was “ready to go on a hunting spree”.

Ms Matteo said it took Ms Hinrichsen 36 seconds to respond “that if it’s ‘to do him’, he has her permission”.

She told the jury Ms Hinrichsen was “far from talking Mr Skinner down” in the messages that followed.

Ms Matteo said Mr Skinner had twice previously threatened to take a knife to Mr Hinrichsen.

Other earlier text messages included one from Mr Skinner that read: “Next move, he’s dead. I am serious”, to which Ms Hinrichsen responded: “I was waiting for you to go into the kitchen and grab a knife.”

In Mr Skinner’s response, he said: “I will f---ing stab right in the f---ing neck. I don’t give a f---.”

Ms Matteo told the jury there was “no single answer” as to why Ms Hinrichsen did not just leave her husband, but reasons likely included that he had not allowed Mr Skinner to move into the marital home.

She said Ms Hinrichsen had also taken out an insurance policy during a cold call in mid-2018, which included a $50,000 payout in the event her husband died from anything other than a natural cause. Ms Matteo told the jury Ms Hinrichsen had then twice contacted the insurance company – including to ask whether life insurance was part of the policy – in the weeks before her husband was killed.

Robert John Thrupp. Picture: Nine News

Gavin Scott Skinner. Picture: Nine News

The jury heard Mr Skinner and Mr Thrupp were each “significantly affected” by methamphetamine at the time of the alleged murder, while Mr Hinrichsen had high levels of prescription pain medication in his system and was in a “significantly sedated state before he was killed”.

It heard CCTV, phone data and phone tower evidence could place Mr Skinner and Mr Thrupp at Mr Hinrichsen’s house at the time the prosecution alleges the murder occurred.

Grant Algie SC, for Ms Hinrichsen, told the jury the “critical issue” for them to consider was whether she was part of an agreement or plan to commit murder in the early hours of the day her husband died.

Bill Boucaut QC, for Mr Skinner, asked the jury to keep an open mind “right until the very end” of the trial.

The trial, before a jury of 14 and Justice Sophie David, is expected to continue for about four weeks.