"The verdict you reached was well and truly justified," the judge said.
Hirini was remanded in custody.
Her sentencing date is yet to be confirmed.
Hirini stood trial on five counts of injuring with intent to injure, a charge of wounding with intent to injure, one of cruelty to a child and two of assault in relation to allegations made by the young man, now aged 20.
The Crown alleged Hirini's abuse of the teenager was constant from the start of the boy's placement with her and her late husband as a 14-year-old in May 2008, until he was 17 - when he finally fled from a serious incident on July 3, 2012.
Counts one to three in the charge list were representative of ongoing offending throughout his placement.
Count one, assault, covered allegations that she hit him, poked him in the eye, struck him with a gumboot, punched him in the stomach, and threw a TV remote and a phone at him.
Count two, injuring with intent to injure with a knife steel, represented numerous incidents in which she hit him with that implement and was evidenced, the Crown said, by the numerous scars that covered the boy's body and DNA evidence found on the steel.
Count three, of child cruelty, covered allegations she poured substances such as dishwashing liquid, salt and curry powder down his throat, locked him in a room at night and forced him to wear a nappy or urinate into a bottle.
It also covered the abusive and directive way Hirini was said to have made the boy do an unjustifiable amount of household chores, including one in which he was set the impossible task of wringing out wet washing into a bucket without dripping water on the floor.
When he faulted, Hirini took away items of his bedding and made him stand out in the cold in a wet T-shirt. He had to sleep in the T-shirt with only his mattress left for bedding.The rest of the charges against Hirini were related to actual alleged incidents.
Count four, assault, related to an incident in which she and her husband were seen punching the complainant by the older brother of another boy placed in Hirini's care.
The new boy phoned his brother to collect him on the first day of his placement, saying he was scared to stay at the house because of the abuse the complainant was suffering. He never returned.
Count five, injuring with intent to injure, alleged the complainant's hand was struck with a hammer.
Count six, assault, alleged Hirini knocked out the boy's lower front teeth using a hammer and the knife steel in about April 2012.
Counts seven, eight and nine, two of injuring with intent and one of wounding with intent, all related to the July 3 incident in which Hirini allegedly lacerated the teenager's finger with a butcher's knife, scraped the inside of his mouth with a cutlery fork and struck him about the head with a knife steel, knocking out his front upper teeth.
The jury found Hirini not guilty of counts five and seven. Referring to count seven, the July 3 injuring charge that alleged Hirini struck the complainant with the knife steel, counsel Leighvi Maynard said in his closing address to the jury that the complainant did not mention that injury when he arrived at a friend's place of work about 500 metres away soon after it allegedly occurred. He seemed more focused on an injury to his hand.
Two other witnesses, Hirini's mother and niece who were at the house where the incident was said to have occurred, said they had not seen any injury to the boy before he ran off.
The complainant's DNA, found in blood stains on the knife steel, could have got there by any means.
The boy was helpful around the house and had been present on numerous occasions when meat was being prepared.Of the other injuring charge on which Hirini was found not guilty - charge five, which alleged she struck his hand with a hammer - Mr Maynard said there was no DNA found on the hammer said to have been used.
A friend of the complainant, who gave evidence, said she inquired of him why his hand was swollen.
He told her it was because he had been fighting.
The injury was consistent with that claim, Mr Maynard said.
- Gisborne Herald
