Police have named the baby who died in Starship Hospital on Friday evening.
He was Chance Kamanaka O Ke Akura Aipolani-Nielson.
Chance was admitted to hospital on Wednesday night.
Police believe the baby's injuries were not an accident, and launched a homicide investigation after his death.
Detective Inspector Aaron Proctor said investigations are continuing into the circumstances.
Anyone with information that could help is asked to get in touch with police on 105 and use the reference Operation Angora.
A post-mortem was due to take place yesterday.