He would leave it up to the coroner to decide if the pair's names should be made public, he said.
Police had previously said the couple were aged in their late 50s and were originally from India.
Mr Ferguson described the case as "bizarre".
"One of the challenges was the denial by the spouse that it was her husband and police had to do a lengthy identification phase," he said.
"At this stage we are not looking at it as a homicide. We've got a lot of our fingerprint and DNA results back and we are pretty comfortable with the identification - that it was the woman's husband. "
Mr Ferguson said the man had been having health troubles and the coroner would rule on the exact cause of death.
His wife, meanwhile, had "mental health issues" and would not admit he was gone.
"That was the twist or sticking point in the investigation. She was saying, 'that's not my husband, this is a stranger that arrived the day my husband disappeared'.
"She was feeding and bathing this decomposing body."
Mr Ferguson said this probably went on for six weeks or more.
Officers had to use dental records, but in New Zealand there is no national database. Instead, investigators had to call around to find where these were held.
The man's wife hadn't been diagnosed with any specific illness but had, perhaps in grief, convinced herself her husband wasn't dead.
It was also possible her actions were a form of Hindu cultural ritual, Mr Ferguson said.
The body was found after neighbours complained of the smell in August.
A woman who lived nearby said she was still traumatised by what happened. She said the pair were good friends of hers and she briefly saw the woman yesterday.
No words could describe the smell coming from the man's house, another neighbour said. He didn't know the dead man well, but said he was "harmless" and had lived in the area for only a year or so.