The Children's Commissioner said the bravery of one child led to a Child Youth and Family caregiver being convicted of 21 charges of child abuse.
Taite Kupa, 57, was found guilty of charges relating to sexual and physical abuse of children in his care in Whangarei yesterday.
Children's Commissioner Dr Russell Wills told Newstalk ZB Kupa set out to keep his offending secret, but a child spoke out about the offending.
"Vetting and screening these days is very comprehensive. [The offending] happens because someone doesn't have a record and then they have to set out systematically to avoid detection.
"The way we catch these guys is because one brave child tells someone, often it's their social worker, and we believe them."
Dr Wills said Kupa breached the trust of the children in his care and of the Children's Commission.
