The inquiry was announced after the Herald revealed in June controversial comments made by Haumaha during the Operation Austin investigation in 2004.
Haumaha was friends with Brad Shipton, Bob Schollum and Clint Rickards from their time together in the Rotorua police station in the 1980s.
Louise Nicholas accused the trio of raping her in group sex sessions and the police opened Operation Austin to investigate the claims, while the Prime Minister Helen Clark ordered a Royal Commission of Inquiry into police culture.
Shipton, Schollum and Rickards were acquitted on charges laid from Nicholas' evidence, but the jury did not know Shipton and Schollum were already in prison for raping another woman who came forward to Operation Austin.
Haumaha was interviewed during the ground-breaking investigation and spoke highly of his friends, describing Shipton as a "softie" and Schollum as a "legend" with women.
Another police officer told Operation Austin that Haumaha - who was appointed to the senior role by Police Minister Stuart Nash in May - described Nicholas' allegations as "a nonsense" and that "nothing really happened and we have to stick together".
The Commission of Inquiry, led by Dame Margaret Bazley, made 64 recommendations to change a police culture which was sceptical of rape complainants.
Dame Margaret also recommended the police progress in implementing the changes be monitored for 10 years. The oversight by the Auditor-General ended this year.
The historic comments by the recently-promoted Haumaha were at odds with the change in police culture since the Bazley Report.
He apologised for the comments which he said do not reflect his values, with Police Commissioner Mike Bush adding Haumaha had been a "relentless" advocate to change police culture and leadership.
However, Police Minister Stuart Nash said he was unaware of the "deeply disappointing" comments when he gave Haumaha's name to the Prime Minister Jacinda Ardern for the deputy commissioner role.
The Acting Prime Minister Winston Peters soon announced an inquiry into the appointment process but not the suitability of the candidate.
The inquiry has been dogged by questions over Haumaha's links to the New Zealand First party and the resignation of the first head of the inquiry, Pauline Kingi.
The inquiry was extended from six to 11 weeks when Scholtens asked for more time to consider allegations of bullying against Haumaha reported by the Herald.
Three women walked out of Police National Headquarters in June 2016 and refused to return because of Haumaha's alleged behaviour.
Scholtens considered the 2016 allegations in her inquiry, but only in terms of what information was potentially available during the recruitment process which led to Haumaha's appointment in May.
A second inquiry by the Independent Police Conduct Authority is now investigating formal complaints laid by two of the women.
The policy analysts - two from the Ministry of Justice, one from Corrections - were working on a joint project based in the Māori, Pacific, Ethnic Services division run by Haumaha, a superintendent at the time.
Alleged verbal bullying contributed to the women leaving PNHQ in June 2016, feeling "devalued and disillusioned".
The IPCA report is expected to finish the investigation by the end of November.
