A man and woman so in love and "desperate" to be together conspired with a friend to kill her husband in a horrific stabbing where part of his scalp was found beside his body, an Australian court has been told.
Tanya Hinrichsen, 43, Gavin Scott Skinner, 46, and Robert John Thrupp, 47, were all charged with the murder of Steven Hinrichsen after his body was discovered at his Nathan Court home in Adelaide just after 9am on December 15, 2018.
The trio previously pleaded not guilty to the grandfather's murder.
During their Adelaide Supreme Court trial opening, the 14-person jury heard the 63-year-old victim — who required a wheelchair and walking frame after recovering from surgery — was stabbed to death by a person or people who did not force entry into the home.
Steven Hinrichsen was left with a smashed photograph of himself on top of his bleeding, mangled body.
Prosecutor Carmen Matteo said the gesture showed the killing was "angry and personal".
She said the victim's body was found in an "unnatural position" with stab wounds to his head, chest and back with significant blood stains left on the floor, walls and lounge room furniture.
The court also heard a part of Steven Hinrichsen's scalp was cut from his head and found on the floor beside the body when police arrived at the scene.
The prosecutor said the victim had high levels of prescription pain medication, including tramadol, and would have been significantly sedated before his death.
Matteo said Tanya Hinrichsen and Skinner were lovers who "wanted and planned" the murder with the help of Skinner's friend Thrupp.
She said the lovers were open about their relationship, with Tanya referring to the younger man as her future husband and wore his engagement ring.
Matteo said the Tanya even told Steven Hinrichsen that she wanted to leave him to be with Skinner.
"Mr Hinrichsen was killed because he was in the way of (his wife) and Mr Skinner's wish to be together," the lawyer said on Monday.
"He was an inconvenience."
Numerous text message exchanges from 2018 were read aloud in court, which Matteo said revealed the "romantic relationship" between the pair.
"There is no reason, no question, no answer, no logic while I love YOU," one message from Tanya Hinrichsen to Skinner read.
Just two days before the victim's death, his wife proposed that Skinner be allowed to sleep with her in the marital home.
The prosecutor said there were "overwhelming" possible reasons why the lovers planned to kill the victim instead of Hinrichsen divorcing him.
They included: Hinrichsen's disapproval of separating from his wife and of her new lover; that Skinner and Tanya Hinrichsen had nowhere to live; the woman's responsibility to care for her husband; and money.
The jury heard the accused woman would benefit from a $50,000 accidental death insurance payout from her husband if he died not from natural causes.
The prosecution claimed Tanya Hinrichsen contacted the insurance company on a few occasions in the lead-up to her husband's death — including a phone call three days before the murder — asking about her entitlements.
The court also heard there were two occasions in the month before Steven Hinrichsen's death where he was assaulted by Skinner, both within a 10-day period.
After the first alleged occasion, Tanya Hinrichsen texted Skinner saying: "He's alive but has a bruised cheek."
Her lover replied, saying "It should be the right hand side" and asked if he was walking around.
After Tanya Hinrichsen replied saying her husband claimed he was bashed outside, Skinner's message read: "WTF ... it was in your bed ... the lying f*** ... I might have to do a better job next time."
The court heard on a separate occasion, text messages between the pair began when Tanya Hinrichsen said her husband "really needs to go", prompting Skinner to reply: "I can do that tonight. Not a problem ... a knife to the throat should do the job."
"Not only was he (Mr Hinrichsen) in the way, not only did Tanya Hinrichsen and Gavin Skinner need him to be out of the picture to further their relationship ... he has also clearly sparked a deep anger in Mr Skinner," Matteo said.
"Ms Hinrichsen came to know the depth of that anger. Skinner expressed it to her in countless messages. She had seen it up close and knew how to exploit it."
The court heard Thrupp's daughter, Rachel, would give evidence at the trial and claim she was with the trio the night before Steven Hinrichsen's dead body was discovered.
Matteo said the young woman visited Steven Hinrichsen's house with the accused trio to pick up some of Tanya Hinrichsen's belongings so she could live with Skinner, Thrupp and his daughter.
"While Miss Thrupp was packing some items from the fridge, she will tell you she saw Mr Skinner holding a knife and a cloth of some kind."
Grant Algie, for Tanya Hinrichsen, said the central issue of the case was to determine if his client was in fact part of a plan or agreement to kill her husband.
"What were her motivations or intentions? What did she say to people, either orally or by text, and what did she mean in relation to what she might have said," the defence lawyer said.
"Even more than what she might have said or her motivation might have been, what did she do? Look for evidence of what she actually did that makes her guilty … or what she did not do."
Algie said there would be "no issues" with the fact Tanya Hinrichsen was married to the deceased, had a relationship with Skinner and that there were text exchanges between the two of them - many of which may not paint his client in a "favourable light".
William Boucaut, for Skinner, told the jury much of the evidence would not be disputed but reminded the jurors the Crown opening was not evidence.
"Don't become lost by what has been put to you by the prosecution," Boucaut said.
"You have not heard any evidence and keep an open mind until the very end of this case. If you don't ... the trial will not be a fair one."
Thrupp's lawyer Chris Weir did not make any opening remarks.
The trial continues.