A homicide investigation is under way in Taupo as police try to piece together what led to the death of a five-week-old baby.
Jayrhis Lock-Tata died in Auckland's Starship Hospital on Saturday.
Interim post-mortem results released on Wednesday show the death was non-accidental.
Detective Senior Sergeant Greg Turner says it is too early to speculate on what caused the baby's injuries, but there was not a medical reason for his death.
He says the boy's parents have been spoken to and the extended family is also co-operating with police.
Mr Turner says two other children, aged 15 months and five years, are being cared for by other family members.
He says the inquiry is likely to take some time and police are working closely with the Department of Child, Youth and Family Services.