Child Youth and Family says it was unable to check on the wellbeing of a two-year-old boy before his death because he and his mother could not be located.
A homicide investigation is underway into the death of James Lawrence at his home in the Auckland suburb of Orakei on Monday morning.
Child Youth and Family says the boy came to its notice a month ago and attempts were made to find him and his mother.
Other agencies were consulted and several visits made to their home.
Child Youth and Family says despite that, it was unable to speak with the mother or check on the wellbeing of James Lawrence.
St John Ambulance says parademics were called at 11am on Monday following a report that a child was not breathing.
The results of a post mortem have not been released.