Mr Thakare did not understand what the pair were saying, but told the authority that Mr Misiaita's body language was aggressive and his tone was mocking.
But Mr Misiaita said when he told the prisoner there was no need to swear and repeated his question, the prisoner said he had better shut up or he would "eat the chair" when the inmate stood up.
When the inmate moved to stand, Mr Thakare said Mr Misiaita stepped forward and struck the prisoner with a direct, hard blow to the centre of his face, hard enough to make the prisoner lose balance.
Either the blow or something in the immediate aftermath also caused the inmate to bleed heavily from his nose.
Mr Misiaita said he acted before the inmate could hit him with a chair by performing a pre-emptive action he called a standard control and restraint - which was placing his hand just below the prisoner's chin and attempted to push him against the wall.
The unit manager, Gary Stock arrived and instructed Mr Misiaita to leave, which he eventually did, but only after he and the prisoner continued to argue.
An investigation was launched by the prison manager Grace Smit.
Mr Misiaita told investigating officers that after the prisoner threatened him with the chair, he feared for his safety.
"I wasn't really sure if he was going to follow on with what he was saying he was going to do, but to me I'd rather stop him there ... I was being intimidated and I was being abused ..."
He said he had a "spilt second" to decide what to do to protect himself, and in hindsight would have done the same thing again.
His union, the Corrections Association NZ said the incident happened at the end of a long day when both prisoners and staff were tired and the inmate had used words that were "particularly insulting" in the Samoan language and culture.
But Ms Smit found Mr Misiaita had committed serious misconduct; in that he had used violence against the offender and used threatening, abusive or insulting behaviour to a person in the workplace.
The authority agreed with the investigation's findings and ruled Mr Misiaita was justifiably dismissed.
The Corrections Department human resources general manager Vince Arbuckle said they were pleased with the authority's decision.
"We remain committed to high standards for all our staff.
"It is important that everything we say and do, we do with integrity, so that we act as role models.''
