A man has been jailed for at least 27 years and nine months for using a samurai sword to brutally murder his father in northern NSW so he could claim his life insurance.
"The offence was carried out with a cold-blooded determination scarcely imaginable to ordinary members of the community guided by moral and ethical standards inherent in most human beings," Justice Peter Hammill said on Friday.
A NSW Supreme Court jury sitting in Lismore in 2017 found Michael Phillip Martin, from Esk in Queensland, guilty of murdering Michael Anthony Martin, 46, at Murwillumbah in northern NSW in June 2014 and of the attempted murder of him in April of that year.
He also was found guilty of causing grievous bodily harm to his father's flatmate, Edmund Andrew Manning, during the botched murder attempt.
The father, an alcoholic and drug user for many years, neglected his son and they were estranged for many years because of the highly dysfunctional relationship.
In late 2013 the son re-established contact and in February 2014 he took out three insurance policies - with a total value of $2.5 million - over his father's life.
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"I am satisfied beyond reasonable doubt that he had in his mind the possibility that he may arrange to have him killed or to murder his father himself," the judge said.
Both the sleeping father and Mr Manning sustained life-threatening injuries in the April 2014 attack which the judge found involved the son and at least one, possibly two other people.
Before the later fatal attack, father and son dined at a local hotel before returning to the Murwillumbah flat.
"At some stage, Mr Martin attacked his father with a bladed weapon causing multiple penetrating injuries, including a chest wound which penetrated his heart .. and caused his death," the judge said.
"I am satisfied that the weapon used was a katana or samurai sword."
Justice Hammill said after the failed murder attempt, Martin saw first-hand his father wake from a coma and suffer as he slowly recovered from his life-threatening injuries.
"Even then, Mr Martin was not diverted from the course of killing him for financial gain.
"The moral delinquency involved in this course of conduct is staggering."
The judge set a maximum term of 37 years.