Michael Joseph Davies will spend a minimum of 19 years in jail for brutally bashing his long-time friend to death on a secluded Puhoi hill - after swearing at the dead man's 76-year-old mother during his sentencing.

Davies, also known as Michael Waipouri, was last month found guilty by a jury of kidnapping and murdering Lance John Murphy in November 2015.

Describing the murder as "shockingly callous and brutal", Justice Anne Hinton in the High Court at Auckland on Wednesday ordered Davies, 52, to serve life imprisonment with a minimum of 19 years and a concurrent eight-year sentence for kidnapping.

As her victim impact statement was read to the court, Mr's Murphy mother, Mary Murphy, 76, held a picture of her son and stared at Davies, before calling him "a cowardly a**hole".

Becoming angry at further comments from the gallery, Davies fired back, "F**k you, bast**ds", and was temporarily removed from the court.

Statements by Mr Murphy's mother, daughter and sister were read to the court.

Each had suffered serious health issues in part caused by stress from Mr Murphy's death, including a heart attack, depression and relapse of cancer, they said.

Each also told of sleepless nights, unable to put from their minds thoughts of Mr Murphy's final moments as he was "brutally murdered by a man we all trusted".

Justice Hinton noted Davies had been jailed before and had 91 convictions for offences, including assault and kidnapping, but did not increase his sentence because of them.

His imprisonment follows a trial filled with, at times, bizarre testimony.

The Crown accused him of luring his friend of more than 30 years away on a false errand to buy drugs before attacking, cuffing and tying a hood over his head.

Then on a remote hill, at Puhoi, north of Auckland, Davies repeatedly beat Mr Murphy with a baseball bat, before using a heavy tree branch to deliver three powerful finishing blows that caved his skull in.

Davies lawyers had hoped to prove it was self defence.

Davies and other witnesses claimed Mr Murphy was a hitman with 10 kills including the well-known cold case death of Jane Furlong.

Mr Murphy was also possessed by demons and had threatened to kill him, Davies said.

His co-accused, Steve Gunbie, who in March was found not guilty of helping Davies kidnap Mr Murphy, sat in the public gallery with friends.