A 3 News investigation has revealed more than a dozen Corrections staff were under scrutiny for alleged criminal behaviour at the start of the year.
Information released under the Official Information Act also shows multiple sackings for misconduct and criminal activity.
Presently a male prison guard has been stood down pending his trial for allegedly assaulting an inmate at one of New Zealand's toughest state-run jails.
The figures don't include Serco employees, and Greens corrections spokesman David Clendon says while the attention has been on Serco, these findings show problems are everywhere.
"Serco has been criticised and quite justifiably, but the public system is far from perfect. We have some serious problems in our corrections system."
Corrections has just over 7700 workers, including prison officers, probation officers and support and office staff.
The department declined to provide job titles for any of the people being investigated or any of those dismissed.
Last year, 11 Corrections workers were dismissed for criminal or conduct issues. Sixteen staff were being investigated and subsequently resigned. And 21 staff were given warnings for criminal or conduct issues, of which five of those were final warnings.
Corrections Association president Beven Hanlon says these figures are not just a reflection of our prisons, but every workplace environment.
"The key is that we are rooting these people out."
Corrections say the vast majority of its staff fulfil their duties with integrity and commitment.
But it has increased pre-employment screening by credit-checking some staff, and is using integrity and conflict of interest questionnaires.
Mr Clendon believes the tough working environment in prisons and low staffing levels in particular are driving experienced staff out.
"It suggests to me that Corrections is having to scrape the bottom of the barrel to employ replacements for those people - experienced people who are simply saying 'enough' and leaving the service."
And he's renewed calls for a prison inspectorate that's entirely independent of the Corrections department.