A baby is critically ill in hospital after being seriously injured at a house in Wairoa in northern Hawke's Bay.
The four-month-old is being treated at Starship Hospital in Auckland and has life-threatening injuries.
Police and forensic experts on Thursday completed a scene examination of a house in Lucknow Street.
Officers are working closely with the family, medical staff, and Child, Youth and Family to establish the circumstances which led to the boy's hospitalisation about 9.30am on Saturday.
Police are not releasing any information on his injuries at this early stage of the investigation.