He appealed the conviction, which was denied.
His family told The Daily Post yesterday they had hired former Waikato CIB Detective Senior Sergeant Bruce Currie, now a Hamilton private investigator, to review the evidence.
Family spokeswoman Alaina Howes said in a statement the family believed there were several unanswered questions relating to the evidence and "hopefully these can be resolved by the review currently being conducted".
Ms Delzoppo's family say they are baffled by the move.
Her mother, Anita Delzoppo, said they were trying to move on with their lives without their beloved daughter, sister and mother.
She has a room set up with all her daughter's photographs and favourite things.
"Not a day goes by we don't think about her ... I'm utterly surprised and disappointed. We want to be able to move on with our lives. It's always there in the back of your mind ... Why dig it all up again?" she asked.
Her daughter's death and the ensuing trial took a heavy toll on her health but things were slowly getting back on track for them, until now, Mrs Delzoppo said
"It took a lot out of my life. I've got a lot of memories though."
She fears such a review will set Ms Delzoppo's son, Drew, back. He had slipped into a dark patch after his mother's death, she said.
Drew is now living overseas.
"He took a long time to recover. Things got bad and he closed up and became withdrawn. He doesn't need this ... we are so proud of him."
Ms Delzoppo's sister, Annie Wright, said through tears she couldn't believe Mills' family were reviewing the case as her sister's death was a culmination of years of abuse at his hands.
"There was history. Her self esteem was worn down. He picked away at her slowly. It was a lead up to this whole nightmare. It was a train wreck waiting to happen."
Ms Wright said life had been difficult without her sister.
"The spark has just gone out of life. You might be laughing and smiling but something in the back of your mind isn't ... we have to move on."
Meanwhile, Detective Inspector Mark Loper, who was the officer in charge of the case, said police were not aware Mills' family would be taking this action.
"They did not come to us and ask any questions when maybe we could have answered some of them. I am not sure what questions remain unanswered."
Mr Loper said Mills and his lawyer had disclosure of evidence from the police and were entitled to cross examine anything that was brought up in the trial.
"We collected evidence, put it before the court and it went to trial."