Children's Commissioner John Angus has told an inquest into the death of the Kahui twins that those living with, or close to, abused children should be held to account if they fail to take reasonable steps to protect them.
The inquest into the deaths of three-month-old Chris and Cru Kahui in 2008 resumed on Monday.
Coroner Garry Evans asked Mr Angus whether health professionals should be legally required to report to police all cases where they have reasonable grounds to believe a child has been abused.
Dr Angus replied that internal procedures already require such action and the problem is not how agencies respond to abuse, but how they assess risk in the first place.
Dr Angus also told him he fully supported the Child and Family Protection Bill which would hold those close to the child accountable and prevent the creation of a ''wall of silence'' around the perpetrator.