Twenty years ago, someone entered Christchurch mother Angela Blackmoore's home and stabbed her more than 39 times.
Her killer has never been identified, and police are hoping that the anniversary, or changing loyalties, may prompt someone to come forward.
On the night of 17 August 1995, Angela was at home with her with two-year-old son Dylan, while her partner, Laurie Anderson, was at work.
When Mr Anderson returned home he found the 21-year-old dead on the kitchen floor, and her son still sleeping in bed.
Mr Anderson, who still lives in the same Wainoni house, said people often questioned how he could stay there - but there were positive memories as well as negative.
"We lived in this house as well. We had positive memories in this house as well," said Mr Anderson.
"You can't condemn a house because of one night. The house didn't murder her, it's the people who came in who murdered her."
Solving the crime would not make a huge difference to his life now, he said, but it would mean a lot for her son to have some answers.
Dylan now goes by another name, which Mr Anderson does not wish to make public. He said while Dylan was not his son, he had remained involved in his life, and had tried to support him as best he could.
"It's a commitment to Angela and her memory that I took her on as well as her family, and I gave him the best protection so he had a chance to grow up and have a decent life as well."
Mr Anderson said he believed the only way the case would be solved was if someone confessed, or told the police what they knew. He was certain a lot of people knew more than they were letting on.
Detective Sergeant Todd Hamilton said someone entered Angela's home and murdered her in a very brutal way. The weapon has never been found, and there was no sign of forced entry to the house.
Mr Hamilton said new information did continue to trickle in, and he hoped that the anniversary may prompt someone to come forward.
"In 20 years people's lives change a heck of a lot - whether their allegiances change, whether their loyalties change and they now want to come and talk to the police, or whether we have spoken to them previously and they perhaps want to say something different from what they said originally, because of certain reasons back then. We would be very grateful to hear from them."
There was an extensive scene examination at the time of the murder and reports of bloody footprints and unidentified fingerprints, but police are reluctant to say whether any of the evidence is able to be re-examined using modern techniques.
Detective Inspector Tom Fitzgerald said it was not as straightforward as constantly retesting things as technology evolved.
"You have to have the background work. You have to put offenders there. We have to have to identify offenders. Just because we have a forensic hit, (it) is not the solver of homicides. It's not CSI."
Mr Fitzgerald said police would not reveal whether they had any hits from the evidence they had, as they did not want the offender to know everything they knew.
The Canterbury region has 11 unsolved homicides dating back to 1916. Mr Fitzgerald said none of them were cold cases to the officers in charge, who were always looking at ways of finally putting them to rest.