An investigation by the Ombudsman into an assault at Mt Eden remand prison has found multiple failures by Corrections, which in turn has told its contractor Serco to apologise to the injured prisoner.
The segregated prisoner was assaulted twice in early 2013 by mainstream inmates who got into the yard but the jail's inquiry into how it happened didn't begin until October that year.
The assaulted prisoner's lawyer, Craig Tuck, told Checkpoint the man was knocked out, as well as suffering other injuries.
Ombudsman Dame Beverley Wakem has finished her investigation and castigated the Corrections Department for failing to properly look into the assaults.
Mr Tuck said his client was one of many who had contacted him with concerns, wanting to be moved from the prison.
He said it had highlighted bigger, systemic failures within the running of the prison.
Mr Tuck said CCTV footage had either disappeared or was destroyed.