Man jailed for 'monstrous' murder of Angela Blackmoore 25 years ago

A man has been sentenced to life in prison for the "monstrous" murder of a Christchurch mother in a crime that went unsolved for almost 25 years.

Jeremy Powell, 45, was sentenced to life in prison with a minimum non-parole period of 10 years in the Christchurch High Court on Wednesday morning for the murder of 21-year-old mother Angela Blackmoore.

Powell pleaded guilty to her murder in February.

The cold case was opened up after police appealed for more information on her death nearly a year ago, offering a $100,000 reward.

Powell fatally stabbed and bashed Blackmoore in her Wainoni home in August 1995.

He apologised to Blackmoore's family through his lawyer at sentencing on Wednesday morning, saying he was terribly sorry for what happened.

In his victim impact statement, Blackmoore's partner Laurie Anderson told the court there was no excuse for the cruel act.

"I will always miss her now," an emotional Anderson said. "She is my love that will never leave me."

Anderson said Powell stole Blackmoore's "new, exciting" future from her.

Justice Cameron Mander said it was a "dreadful and monstrous" killing of a vulnerable woman in her home.

Powell had "deprived a little boy of his mother", Justice Mander said.

"The murder was planned and premeditated," he said. "You armed yourself.

"She would have no idea she would be subject to such an attack."