There will be no immunity from prosecution for a supposed former prison officer willing to shed light on "unlawful execution practices", raised by two inmates on death row, the Attorney-General's Chambers said in court documents filed last week.

In a related document about the alleged unlawful method used, the prison authorities also said there was no known instance of the rope used for executions snapping, which allegedly would have required prison officers to kick the back of the prisoner's neck to complete the execution.