A New South Wales man who shot his estranged wife at close range with a rifle in front of their daughter has been jailed for at least 31 years.

Keith Goodbun, 62, forced his way into the home of his estranged wife Molly Goodbun, 59, at Maitland in the Hunter Valley on October 7, 2016.



Months earlier Ms Goodbun had taken out an apprehended domestic violence order against him after their 40-year marriage deteriorated.



The Supreme Court heard he shot her four times in the head and chest in front of their 30-year-old daughter.



In sentencing him to at least 31 year's jail, Justice Helen Wilson said Goodbun committed a premeditated, cruel and deeply shocking crime, "motivated by deep anger".

"It may, without hyperbole, be described as an execution," Justice Wilson said.

"It was clearly his intention that nothing would stop him from murdering his wife."

She said the offender had a secret key to his wife's house and defied a court order by approaching the property when he knew his wife and daughter would be at home and asleep.

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The judge said "this crime falls in the top range of seriousness".

"Domestic violence is a serious problem in the community," Justice Wilson said.

She said, on average, one woman a week in Australia is killed by a male partner in a domestic violence incident and that the community should be ashamed of that.

Outside court, Molly Goodbun's cousin Rosienne Johnson welcomed the sentence.

"Molly was like a big sister," she said.

"We did so much through our lives together.

"She was always there for everyone."

Shooter often angry with wife

Justice Wilson said Goodbun drove from Taree, on the state's mid north coast, to Maitland to murder his wife.

Molly Goodbun's cousin Rosienne Johnson said school children should be educated about domestic violence. ( ABC News: Jamelle Wells )

She said he burned a caravan that he was living in before leaving Taree.

Goodbun arrived in Maitland about 3:00am, armed with a Winchester .22 calibre bolt action rifle and a large hunting knife.

The court heard his daughter Bionca Simmons was injured wrestling with him on the verandah while trying to get the gun away.

When Ms Simmons tried to give her mother first aid, Goodbun pointed the gun at her and said "get the f*** out of here or you're next, you're lucky I haven't done it already".

Ms Simmons kissed her mother and said "I have to go, I love you" before running next door to a neighbour to get help.

Goodbun then fired more shots into his wife's head "to make sure she was dead".

Justice Wilson said Goodbun was often angry with his wife, yelling at her and damaging her belongings.

On one occasion he ripped the phone from the wall as she tried to call police.

Murderer blamed victim for his problems

The court heard Goodbun yelled, "I hope she f***ing dies, she deserves to die" as his daughter tried to help her mother.

Goodbun stayed at the house drinking gin before police arrived.

He later pleaded guilty to murder and told police his wife was "a piece of shit".

A doctor who assessed Goodbun in jail noted that he was a heavy drinker and a binge drinker who blamed his wife for his problems.

Bald with a long grey beard and wearing a green jumper, Goodbun looked across at family members who were in the public gallery as the judge handed down his sentence.

His maximum sentence is 41 years with a non parole period of 31 years.