The brother of Arthur Allan Thomas says there's no satisfaction in an apology from the incoming police commissioner over old comments he made.
Deputy Police Commissioner Mike Bush will move into the top job in April, taking over from Peter Marshall.
Mr Bush was criticised last year when he praised disgraced officer Bruce Hutton at the Crewe murders investigator's funeral, saying he had integrity beyond reproach.
A Royal Commission found that Mr Hutton planted evidence that led to the wrongful conviction of Arthur Allan Thomas for the 1970 Crewe murders.
Mr Bush apologised in the media on Tuesday for any offence his comments had caused anyone, and said that in hindsight the remarks were probably inappropriate.
Arthur Allan Thomas' brother, Des Thomas, said Mr Bush should say sorry in writing, and address what he calls the police corruption in the Crewe murder case.
"Sooner or later someone, and I think Mike Bush should seriously consider this, is to address the problem that they had with this case. It's not going to go away," he told Radio New Zealand's Morning Report programme on Wednesday.
Police Minister Anne Tolley said on Tuesday the eulogy was a bit of a line call, but paled into insignificance against Mr Bush's 35 years of service.
She said she did not think he would make the same mistake again and the comment should not exclude him from holding the top job.