The trial of Clayton Weatherston was a disgrace as it allowed a killer to continually persecute his dead ex-girlfriend and her family, a women's advocate group says.

Women's Refuge chief executive Heather Henare said Sophie Elliot did not deserve her death and she did not deserve to have her character so "scrupulously undermined".

She said Weatherston's trial "turned justice inside out".

"The killer became the victim and Sophie Elliot was portrayed to us all as he chose to describe her. Unfortunately for Clayton Weatherston, the jury didn't buy it and nor did the hundreds of thousands of New Zealanders who watched him giggling on their televisions," Ms Henare said.

Weatherston was found guilty of the murder of Miss Elliot after he attacked her with a knife in Dunedin on January 9 last year. Weatherston accepted he was guilty of manslaughter, but denied the charge of murder. His defence lawyers claimed he was provoked by Ms Elliot.

"It seems so unfair that we have had no opportunity to hear about the person she actually was. I was horrified to hear her mother described as an unreliable witness by the defence.

"I feel, as I'm sure we all do, great sympathy for Sophie's family under these terrible circumstances," Ms Henare said.

She was referring to a statement by Weatherston's lawyer Judith Ablett-Kerr, QC, who said Miss Elliott's mother, Lesley Elliot, was a "less than reliable" witness because of the trauma she had been through when she saw the scene in her daughter's bedroom.

Speaking after the trial, Lesley Elliott said she found listening to Weatherston giving evidence very hard and also struggled with the fact she could not rebut a lot of what was said by the defence in the trial.

"I know what went on in that room."

The family found it offensive that parts of Miss Elliott's diaries had been read to the court, she said.

"They were her private thoughts. They were her privacy and I think for anyone who writes diaries you don't actually want anybody to read them. And we found that really offensive.

Ms Henare said she believed there would be "a strong and justifiably angry reaction to the way this trial proceeded".

"New Zealanders hearing so many of the details and seeing Weatherston taking the stand will have been absolutely dumbfounded that this remorseless killer has had a platform for his justifications and excuses televised and thoroughly reported by the media," Ms Henare said.

She said there was a need for legal processes that encourage confidence in the legal system.

"Everyone must have a fair trial, of course, but I think we need to be asking whether a trial like this actually represents any kind of justice whatsoever," Ms Henare said.

She said she hoped that Ms Elliot's legacy to the country will be a fairer justice system for victims.