A state inquiry is examining the circumstances of sex offences committed by ex-prison guard Wayne Astill at Dillwynia Women's Correctional Centre, on the outskirts of Sydney.
Astill was jailed for up to 23 years this year for abusing his position and assaulting prisoners for several years until his suspension in 2019.
Former prison guard Wayne Astill was jailed for assaulting inmates at a women's jail.
It was an open secret within the jail that he engaged in sexual acts with female inmates, the inquiry previously heard.
Peter Severin, the former NSW Corrective Services commissioner, told the inquiry on Monday he was very concerned to hear evidence indicating criminal conduct by guards could have gone unnoticed by the agency due to a lack of resources.
The inquiry was told of resourcing issues in the prison system's investigations branch with respect to intelligence analysts, particularly in 2018.
"That has never been brought to my attention, quite frankly," said Mr Severin, who was the state's prison boss for nine years until 2021.
"If that was information that I would have been made aware of, with $2.1 billion budget you could have found resources to actually make sure that never happens.
"That being said I was certainly aware that there were resource pressures."
Retired judge Peter McClellan, who is helming the inquiry, put to Mr Severin that a lack of resources enabled "serious issues to sit and not be looked at".
"What went wrong to allow that position to emerge?" Mr McClellan asked.
"I would have expected that the investigations branch would have brought this ... criminal intelligence to the attention of their line management," Mr Severin replied.
The probe, set up after Astill's sentencing, has already heard more than 300 extra cameras were needed to address security shortfalls in the section of the prison where his offending took place.
A final report is set to be handed down in December.
The inquiry continues.
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National Sexual Abuse and Redress Support Service 1800 211 028