Convicted murderer Martin Cranswick Schofield has been deemed a high-risk offender who shows a lack of remorse for the brutal murder of his partner.

The 50-year-old was sentenced to life imprisonment, with a minimum non-parole period of 11 years, for beating Katrina Drummond in the head with a hammer in Taupo on April 14.

Convicted hammer killer Martin Schofield has been sentenced to life imprisonment with a minimum parole period of 11 years. Photo: Bruce Mercer/stuff.co.nz

Katrina was struck in the head seven times with a claw hammer after Schofield 'lost it” when she told him she was seeing another man.

Before the murder, Schofield had used a Stanley knife to carve derogatory words onto the bonnet and roof of Katrina's car and slash the back seats.

Speaking at sentencing in Rotorua's High Court yesterday, Justice Christopher Toogood said: 'Grabbing a builder's claw hammer from the workbench, you returned to the house through the back door and searched for Ms Drummond in the house.

'You found her in the main bedroom, where she was standing at the foot of the bed looking away from you.

'You entered the bedroom and struck Ms Drummond on the back of the head with the hammer, with sufficient force to cause her to fall to the ground. She landed face down. You then stood over her and directed several blows to the back of her head.”

Schofield then dropped the hammer and drove himself to Taupo Police Station to hand himself in.

He admitted the killing and said Katrina's 'use of alcohol was a major issue in the relationship”.

In victim impact statements read to the courts, Katrina's daughters said the damage caused by Schofield is irreparable.

'No amount of remorse, apology or reparation will ever fill the hole that you have left,” read the statement.

A pre-sentence report presented to Justice Toogood assessed Schofield as being at 'high-risk of reoffending” based on the seriousness of the offence and his lack of genuine remorse.

'The report writer says that, despite pleading guilty to murder, you made numerous attempts during the interview with her to justify your actions and to shift the blame onto your defenceless victim,” said Justice Toogood.

'You said Katrina was an alcoholic and that her alcoholism left you physically and mentally drained. You said you lost it and snapped when she told you she was seeing another man.

'The report writer expresses concern at your inability to acknowledge your responsibility for the severe and deliberate violence of the offending, or the full extent of the consequences of Ms Drummond's death for others.

'You said you have written to your children and, although you have had no response from them, you think time will heal the damage to your relationship which has occurred.”

Schofield must serve at least 11 years before being considered for parole.