A young son has been robbed of the best father in the world, the High Court at Invercargill heard this afternoon.

Sandy Graham (33) has been sentenced to life imprisonment for the murder of Dale Watene at her Ōtautau home on 16 April 2020.

Her friend, George Hyde (25), has been sentenced to eight months' home detention for being an accessory after the fact for helping dispose of the body.

The pair were found guilty following a four-week jury trial in June and July this year.

Watene went missing from the small forestry town of Ōtautau on 16 April 2020 and was found in a shallow grave in nearby Longwood Forest about a month later.

The shallow grave where Watene was found had bricks placed on top in an attempt to hide the fact the site had been freshly dug up.

Graham and Hyde gave written and recorded video statements to police in the days following Watene's disappearance.

Graham, who had been in a relationship with Watene, claimed the last time she saw him alive was when he left her address on the night of 16 April to go to get more beer.

Hyde claimed he had no knowledge of Watene's whereabouts.

In August, following the discovery of Watene's body, Hyde spoke to officers again and on that occasion gave a completely different account.

He told police he received a phone call from Graham on the night of 16 April. She was upset and asked Hyde to come to her home.

Hyde told police Graham had told him she and Watene got into a fight, he had beaten her up, threatened to kill himself and had killed himself.

He admitted to helping dispose of Watene's body as he did not want Graham to get into trouble for having a firearm.

At the trial Graham's lawyer gave another account of what happened, saying Graham admitted an involvement in Watene's death but it was just a tragic accident.

The Crown's case was Graham knowingly shot and killed Watene following an argument.

Dale Watene was murdered on 16 April 2020. Photo: Supplied / Police

After two days of deliberations the jury found Graham guilty of murder.

The jury found Hyde guilty of being accessory after the fact to manslaughter, finding it was possible he believed the death was accidental.

Hyde's lawyer, Fiona Guy Kidd, told the court today her client had also been manipulated by Graham.

He maintained, that at the time of disposing of Watene's body, he believed the 40-year-old had taken his own life, Guy Kidd said.

Justice Gerald Nation said, before beginning a relationship with Graham, Watene had struggled with alcohol use but had decided to leave that in the past.

Graham was an alcoholic, prone to violence and struggled to form meaningful relationships, Nation said.

"It was a tragedy for Mr Watene that around September 2019 he began a relationship with you Ms Graham," the judge said.

"It has had tragic consequences for your children, who will be deprived of a mother while they are growing up."

Justice Nation said he rejected Graham's claims that she did not know how Watene was shot or that it was an accident.

She had deliberately taken aim at Watene and pulled the trigger, he said.

Graham then set about covering her tracks, including contacting Hyde for help in disposing of the body, sending a message to Watene's cellphone feigning ignorance of his death and contacting his mother feigning concern for her missing son, Nation said.

"There was maliciousness in your lies and the way you suggested other people might have been responsible for his death."

The mother of Watene's son told the court her former partner was the best father in the world.

"The most important day for [Watene's son] was Father's Day.

"It broke my heart last Father's Day when his brother and sister went to their father's for Father's Day and [Watene's son] asked me to take a photo of him next to his father's grave. That was his Father's Day and you caused this," she said addressing Graham.

Watene's final words to his son were "Dad loves you my boy", the woman said.

Graham would spend at least 13 years behind bars.

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