The health chief who died in mysterious circumstances at her Remuera home had contacted a private investigator, the police inquiry has discovered.

Hanna, 63, was found dead in her home a month ago and detectives remain tight-lipped about the inquiry, saying her death remains "unexplained".

Several private investigators have told the Herald that police have contacted them in a bid to confirm if Hanna had enlisted their services.

One investigator, who asked not to be named, said he received an email from a detective on April 12 - one week after Hanna's death on Easter Monday.

"It stated they had information suggesting that the deceased had engaged the services of a private investigator and had we worked for her - we had not.

"But there was also a note found at the house that said 'private investigator' and the name 'James' on it," he said.

A second private investigator said he was also asked if they had worked for Hanna.

"I remember getting a call about was she a client? Had she been a client? The answer was no," he said.

"I'd never heard of this woman before I read she had died in the papers."

Death remains unexplained a month on

Today marks a month since police swarmed a property in Remuera - one of Auckland's most affluent suburbs - on the morning of April 5.

Police went door-to-door asking residents for any information that may shed any light about what had happened.

Hanna's husband, Philip Polkinghorne, told the Herald at the time that he had been the person who found his dead wife. They had been married for close to 30 years.

Police later said the death was still being investigated, but that it was being treated as "unexplained".

Polkinghorne, an eye specialist, said he was being treated as a "person of suspect" in the police investigation.

"As you may or may not know, I am a person of suspect - so i need to talk to my legal counsel whether I should or shouldn't say anything."

Polkinghorne described his wife as an incredibly hard worker and a "magnificent woman" who worked hard for her community.

Hanna worked as a senior health manager, holding roles at the Counties Manukau District Health Board for the past 20 years.

She was working on the Covid response when she died.

Police remained at the Remuera property for more than a week after her death.