An online fundraising page set up to help the family of Blessie Gotingco take the Corrections Department to court has raised nearly $90,000, on its first day.
Tony Robertson is behind bars for at least 24 years for raping and killing Mrs Gotingco in 2014.
A government inquiry this week found no failings in the management of Robertson after his release from prison on child abduction charges, six months before he murdered Mrs Gotingco.
But it said more could have been done while he was still locked up.
Blessie Gotingco's husband Antonio told Newshub's The Nation he believed Corrections was responsible.
"We are going to probably face the biggest challenge of our life, ok because we're planning to continue our fight and probably you know file a civil case against the Department of Corrections in particular, so we're fighting the establishment."
Antonio Gotingco is appealing to the public to donate to his give-a-little campaign.