An early-childcare worker has told an inquest into the deaths of the Kahui twins that their elder brother was not capable of inflicting their fatal injuries.
Chris and Cru Kahui died in 2006. They were three months old.
Their father, Chris Kahui, was acquitted of their murders after claiming his elder son Shayne must have climbed up on the couch and got at the boys.
Shayne was then 13 months old.
But childcare worker Kathryn Stent, who looked after Shayne while the twins were in Middlemore Hospital's neo-natal unit, said on Tuesday that he would not have had the strength to pull himself up onto the couch.
South Auckland social worker Shane Harris, who works for Child, Youth & Family at its Manurewa office, has described the area's child abuse problem as immense.
Mr Harris told coroner Garry Evans that Counties-Manukau District Health Board, where he formerly worked, made at least 20 formal referrals of a serious nature to the agency each week.
Asked why the area had New Zealand's worst rate of abuse, Mr Harris cited financial pressures and feelings of hopelessness as primary causes.
Backing for mandatory reporting
Shine, a child abuse prevention service, says health and education providers must be subject to mandatory reporting.
Spokesperson Rachel Smith, who also works on Auckland District Health Board's family violence team, says only 1% of child abuse cases are reported by general practitioners.
Ms Smith says that is because health and education providers do not share information well and are not trained to recognise the signs of abuse.
Change will happen only when everyone has a responsibility for child protection, not just Child, Youth & Family and police, she says.