Incidentally, she had described him in a report as "vulnerable to abuse" because of the risk he would not be believed if seriously harmed.
Hirini is charged with 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 a young man, now aged 20.
The Crown alleges the abuse was continual from the start of the boy's placement as a 14 year-old with Hirini in May 2008, until he finally fled when he was 17 -- from a serious incident on July 3, 2012.
Most of the charges were representative but three related specifically to that final incident in which the Crown says Hirini lacerated his 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 and yelling "take that!".
It was alleged she similarly knocked out his lower front teeth in April 2012 but explained the injury by saying the boy got into a fight on one of the many occasions he had stayed out overnight.
The social worker witness was also the appointed overseer for two teenage girls placed separately in Hirini's care for about six months -- one during 2009, the other in 2010.
Both said in evidence they were shocked at Hirini's mistreatment of the boy but felt unable and too scared for their own welfare to help him.
They gave damning testimony about their social worker's lack of oversight, one saying she was "useless", rarely visited, made little inquiry of them and spent her time chatting to Hirini -- a friend --while "getting paid for it".
In evidence, the social worker said there was no sign of anything inappropriate about Hirini's parenting.
Crown prosecutor Clayton Walker put to the social worker that CYF had unduly dismissed a report from a school counsellor in 2010 that the boy claimed to have been hit over the head with a knife sharpener.
Despite a paediatrician's report confirming injuries consistent with that claim, CYF dismissed it after the boy exaggerated, saying he had been hit 20 times.
"You had here information that indicated some support for what he was [originally] saying but because his story perhaps grew in the telling, it was determined his account could not be believed or relied on -- so back he went [to Hirini's house]," Mr Walker said.
The social worker agreed with Mr Walker's contention that the boy had accumulated incidents in his mind, then reported them as one.
She dealt with her concern over the complainant's vulnerability by making regular visits to the home six-weekly, she said. She had not noticed other injuries and he seemed to have a reasonable explanation for every little mark on his arms and legs.
She had not seen one of his hands swollen, with fingernails blackened, that another witness described to the court. Mr Walker put it to her such injuries would have been apparent for several weeks.
The witness confirmed to Mr Walker that she left her position in Gisborne because of something that happened at work and that her performance was part of that issue.
The jury is expected to return a verdict later today.
- Gisborne Herald