Forensics were on site for several days following the death, and police could be seen talking to neighbours.
Neighbours told the Herald police asked if they had seen or heard anything unusual, such as car movements. One neighbour said they spotted police towing a red car from the house.
"It sounds like it's a homicide inquiry," former police detective Lance Burdett told the Herald.
"If it's going on for any length of time they would be leaning towards suspicious [death] rather than unexplained.
"If forensics are there every day it is ... possibly suspicious, and more likely probable."
A homicide inquiry does not necessarily mean a murder, Burdett said, but it means someone else may have been involved.
Police will be using this time to first find out how Hanna died, why and then who is involved, he said.
If it's a homicide inquiry, police will need to find someone culpable, he said.
Reasons for a prolonged investigation into an unexplained death could include needing to get hold of medical files, Burdett told the Herald.
A post mortem examination was completed on April 7.
Detective Inspector Aaron Pascoe, Auckland City CIB, said police would continue to investigate the death in the days to come.
"The scene examination remains ongoing at the Upland Road property. This examination is nearing completion and we anticipate it to continue for the next few days."
Hanna's colleagues at the DHB issued a statement today saying she was a "highly respected and much-loved member of staff".
"Pauline held various roles within the DHB since joining in mid-1998 and was most recently seconded to lead the Auckland region's logistic supply chain work related to Covid-19.
"The passing of Pauline has left a large hole in the fabric of our whānau and our thoughts and prayers are with her family and friends at this time."
Hanna will be farewelled at St Mary's in Holy Trinity, Parnell, at 10am on Thursday.
Her death notice states she was a grandmother to two children, and mother of three boys.
It also acknowledges her DHB colleagues and husband, and "eternal friend", Philip Polkinghorne.
Polkinghorne - an eye specialist - told the Weekend Herald he was struggling with her death and that he "just can't think straight".
He said he found his wife of nearly 30 years dead early last Monday morning.
Polkinghorne said Hanna worked all through Easter but they were able to spend some time together on Sunday.
The couple went to Highland Park, where Hanna checked in on one of the vaccination stations before having lunch together and going home. After dinner, the pair watched television together and Hanna helped Polkinghorne write a letter.
"I said goodnight to her. I went to bed and she went to bed. That was the last time I saw her alive."
The following day Polkinghorne got up to make breakfast around 7am. The pair had planned to go to the gym after breakfast.
"Normally I go before her but she wanted to go to the gym at 9am. I think she had a meeting at 10.30. I got up to make her tea and toast – that's what she always had. She is the only person in the world that I know who can have a cup of tea lying on her back," Polkinghorne said.
"Then I found her dead. It was just horrible, horrible, horrible."
Polkinghorne said there were no problems in their marriage.
