The detective who oversaw the investigation into the body of a newborn baby girl found in a recycling centre says he remains hopeful the family will come forward despite the inquiry hitting a dead end.

Tuesday marks one year to the day since the baby, only a day or two old, was found among the rubbish in the Visy recycling centre in Onehunga, Auckland.

Detective Inspector Scott Beard told the Herald police had made extensive inquiries into the death of the baby but remained unable to identify the mother or father.

That was a cause of immense frustration for investigators, who remain committed to finding the mother who may require extensive support, Beard said.

The baby was dubbed Anahera by the community, the Māori word for angel, and has also been called Baby Doe.

It had been carried to full term but the state of her body meant a pathologist was unable to definitively determine the cause of death. As a result, police cannot rule out foul play.

Beard said inquiries into the origin of the large number of rubbish trucks that came into the plant before the discovery of the body could not determine where the baby was picked up.

"At the time it first came in, there was a lot of focus around the rubbish trucks. There was 104 trucks that came into the plant that day.

"Unfortunately, that hasn't led us any further."

Police did find some adult and baby clothing in a blue bag but a public appeal with images of the clothes came to nothing.

Investigators also went down the familial DNA route, Beard said.

But the lack of any names or further information to start with made the analysis difficult.

"It's not as easy as people think."

Analysis of the DNA did return about 300 names with familial links but as yet police cannot say who the mother or wider family are.

The pathologist had also been unable to categorically say what ethnicity the baby was.

Anyone who recognises the clothes the baby was found in was asked to contact the Operation Deer investigation team. Photo / Supplied

Advancements in DNA technology may eventually help police hone in on Anahera's close family, Beard believes.

"Hopefully they'll come forward before then."

The baby's body had suffered trauma from being among the recycling.

"The pathologist's unable to establish the exact cause of death.

"The baby was born within a day or two of us finding her.

"We don't know the circumstances or situation that the mother was in. So we're not coming to jump to any conclusions, or pre-judge, we just want to identify her."

Beard said it was too early to say whether anyone from the family was likely to be charged.

Police have to satisfy the Solicitor-General's guidelines before a prosecution is brought: the evidential test followed by the public interest test.

The first test requires credible evidence on which an impartial jury or Judge could be reasonably expected to convict.

Detective Inspector Scott Beard said he remains worried about Anahera's mother, and hopes she or the family come forward. Photo / Michael Craig

If that test is satisfied, the public interest test must then be met.

The main requirement for the public interest test is the seriousness of the offence, while prosecutors must also take into account whether there are grounds to believe the offence is likely to be committed again.

"It'd be too early to go down that track," Beard said.

He said police's priority was finding Anahera's mother.

"She may still need some support, some counselling, which we can provide. And then let's take it from there."

Beard said police were working with the Coroner's office as to whether and when they could release Anahera's body and hold a funeral service.