Police are investigating how a four-month-old boy from Motueka sustained a serious skull fracture.
An ambulance was called to a house in Motueka, 54km northwest of Nelson, about 11pm on Labour Day Monday after the boy's parents reported he was not responsive.
The boy was transferred to Auckland's Starship Hospital late on Tuesday afternoon.
He had improved slightly but remained in a serious condition, said Detective Sergeant Kevin Tiernan of Nelson CIB.
"The paediatrician can't date the injury, so it could have happened any time even as far out as two or three days," he said. The boy's condition could have deteriorated slowly over the weekend, and it may not have been obvious when the injury occurred.
Police did not know yet what had happened, but had spoken briefly to the parents on Tuesday and would speak to them again in Auckland. They had been very co-operative, Mr Tiernan said.
"We've got to speak to other family friends that visited the address over the weekend, we're doing area inquiries, we're speaking to their family and anyone that may have had some association not only with the child but the family over the weekend."
