Detective Senior Sergeant Mark Loper said as the matter was before the court he could not reveal what injuries Trent had suffered. But 3 News reported the baby had suspected bruising to his body.
Mr Loper also could not detail the circumstances surrounding the infant's death.
But asked if the charge could be upgraded to homicide, Mr Loper said: "It's too early to say yet. Why I say that is the autopsy at the weekend was inconclusive and we are waiting for forensics, so until we get a definite cause of death we won't be able to proceed. At this stage we can't say that this is a death as a result of child abuse. We are still investigating."
Mr Loper said forensic scene examination results could take up to six weeks. He said the family did not have a history of domestic violence and were not known to police.
The brick and tile home where Trent was found dead was empty when the Herald visited earlier yesterday.
The house, which is near a primary school in the quiet Rotorua suburb of Western Heights, had a trampoline on the front lawn.
Neighbours said that despite the odd party when the couple moved in late last year, the man and woman were polite and quiet.
"There was the odd party but we are probably noisier than they are," said one woman, who wanted to be known only as Sandra.
Another neighbour, Mere, said her mokopuna (grandchild) used to play with the 7-year-old boy who lived at the house.
She said that on one occasion the man living at the house ran to another neighbour's place to see if they were all right after seeing smoke coming from the home.
"It turned out they were just burning rubbish, but it showed he cared."
Mere regretted not getting to know her neighbours better. "They could have come to us and asked us for help. We would have helped them if we could."
Police said Trent's body was released to family members on Sunday after the post-mortem.
He was taken to Kaitaia, where it is understood he will be buried today.
