A man sentenced for murder swore "f*** the lot of yous" as he left the dock, making a mockery of his claims of remorse, says the mother of the Rotorua man he killed.

Outside the High Court at Rotorua yesterday, Charmaine Irimoko Burnett said the words were clearly audible to those in the public gallery, and police confirmed Christopher Allan Heenan uttered them.

However, they were not heard by those in the body of the court, or apparently by Justice Timothy Brewer.

He had just sentenced Heenan, 52, an artist, carver and tattooist, to life imprisonment for the murder of Raukawa Newton at Rotorua on October 11, 2007.

Justice Brewer imposed a minimum 10-year non-parole period.

Heenan was found guilty by a jury last month after a 13-day trial.

The court had heard that Heenan was remorseful and had written a letter to his victim's family.

Ms Burnett said if it was passed to her she would refuse to read it. Other whanau members could if they chose to but she advised against it, saying it would obviously be insincere.

Referring to defence counsel John Bergseng's submission that alcohol had played a significant role in Heenan's actions, Ms Burnett said she could not imagine what he would be like when returned to society.

He needed full rehabilitation while behind bars but she doubted he would receive it.

While Heenan had been sentenced as the present law directed, it should be changed to ensure life imprisonment meant just that - life, she said.

"This was a cold, calculated killing, 10 years is not what you call justice in the context of this particular murder," Ms Burnett said.

Sentencing Heenan, Justice Brewer said victim impact statements he had read spoke of a man who was greatly respected by his whanau and illustrated the feelings of deprivation and loss his death had caused them.

He noted Heenan had repeatedly stabbed himself on the night he killed Mr Newton and claimed to have no memory of events. With little physical evidence, it had taken almost two years for him to be arrested.

"You prolonged the ordeal for Mr Newton's family and yourself."