An inmate’s trail of destruction across a prison roof during a night under the stars cost almost $250,000 to repair and earned him a further two years behind bars.

The inmate at Whanganui’s Kaitoke Prison was being returned to his unit on March 26, 2022, when he seized an opportunity to elude staff and scaled a mesh grate to gain access to an area of the roof.

He was well known to guards and his unruly behaviour, at the minimum to high-security prison, began the previous day with an attempted assault on a guard, followed by an argument during a telephone call just before he gained access to the roof and refused to budge.

The prisoner was able to access a wide area on the roof and caused extensive damage to skylight windows, air conditioning units, lighting units, plumbing infrastructure, roofing iron, gutters and fire sprinklers during the night before he climbed down at 1pm the following day.

A full operational review into the events was carried out and police were contacted to consider criminal charges in relation to his actions.

Department of Corrections regional commissioner Liz Hawthorn said the internal inquiry concluded the incident appeared to be spontaneous and there was nothing to suggest it was pre-meditated or planned.

Hawthorn confirmed the area where the inmate accessed the roof, while inside the secure confines of the prison, was outdoors, and he had climbed a mesh grate.

“The prison is considering constructing a caged walkway in this area to help mitigate these kinds of events but this is still to be fully costed.”

While the prison did not have a price for those remedial measures, it had calculated the cost to restore the infrastructure vandalised by the inmate.

“A full assessment of the damage was done and repairs were completed by the middle of 2022, totalling $240,560,” Hawthorn said.

Police charged the prisoner with intentional damage of prison property and he was sentenced to a further two years’ imprisonment.

Hawthorn said the operation review also made a number of recommendations to improve safety at the facility and all of the suggested measures had been actioned already.

The steps included assessing the security risks and access ways at the prison to ensure all solutions had been considered, considering increased staff deployment to mitigate future risk despite staffing levels at the time deemed appropriate, and assessing all CCTV cameras to ensure they were well maintained.

She said staff training in emergency management and incident response was being prioritised for staff as well as developing a better understanding of prison negotiation training.