Wayne Astill was sentenced in March to a maximum of 23 years jail for the rape and indecent assault of nine women while working as an officer at the Dillwynia Correctional Centre in Sydney's west.
The 67-year-old will spend at least 15 years and four months behind bars for abusing his position of authority to commit the sexual assaults over several years until his suspension in 2019.
The NSW government has ordered an inquiry into the case after allegations his crimes were allegedly covered up by colleagues and dismissed by high-ranking managers, allowing the abuse to continue for years.
A senior former judge will lead the investigation and report to NSW Corrections Minister Anoulack Chanthivong.
AAP understands the inquiry will examine whether Corrective Services employees or prison management had knowledge or reasonable suspicion of Astill's offending, whether any steps were taken and whether adequate supervisory systems and oversight were in place.
Mr Chanthivong said he was shocked and appalled by the circumstances surrounding the crimes and the allegations of a cover-up.
"The response to date hasn't been adequate and I'm deeply troubled," he told AAP.
"We've got to move quickly but we're also working carefully in designing this review."
The minister said he would have more to say on the process over the coming days.
Corrective Services NSW said it was unable to comment as matters involving Astill are still subject to an ongoing police investigation but would welcome any inquiry into the circumstances surrounding his offending.
"The conduct for which this former officer has been convicted (is) completely and utterly deplorable," a spokeswoman said.
Since Astill's conviction dozens of women have come forward with fresh allegations of abuse.
Some have reportedly sued the department and had their cases settled with confidential payments.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
