KEY POINTS:
Child, Youth and Family has taken over the care of a 4-month-old boy in intensive care at Starship hospital.
Doctors fear the baby, from Motueka, near Nelson, has suffered permanent brain injury from a skull fracture inflicted some time over Labour Weekend.
Police have interviewed at length his parents, who called an ambulance on Monday night when the baby became unresponsive.
However, they were at a loss to explain how or when the injury had happened.
Detective Sergeant Kevin Tiernan of Nelson CIB flew to Auckland on
Thursday to interview the distraught couple, who are keeping a bedside vigil at the hospital.
He said there had been several adults at the family's home over the weekend and the injury could have been inflicted "by any one of them".
Police were also talking to friends and family, and would re-interview several people, Tiernan said.
CYF has also taken over the care of a second baby living with the couple at the time the injuries were inflicted.
The agency's acting southern regional director, Helen Aitken, said she was unable to comment on events leading to the baby's admission to hospital because of the police investigation.
"However, we can reassure the public that the baby's safety and wellbeing is now our responsibility," Ms Aitken said.
Aitken confirmed a 1-year-old baby from the extended family, who had been living with the couple, had been taken into care while authorities decided on its "best interests".
