Police have failed to find the source of the leaked Don Brash emails.
A police review of the investigation, involving almost 200 interviews, into the publication of the leaked emails from the then-leader of the National Party has been completed and the source of the emails could not be established.
There was speculation of an inside job and Prime Minister John Key says he believes the leaked emails was the work of a hacker.
"I think the computer system was hacked into, that's my view but I can't back that up," he says.
The emails became the basis for a book, The Hollow Men, by journalist Nicky Hager, which later became a stage show.
The review, overseen by Auckland Region Assistant Commissioner Steve Shortland, investigated complaints and allegations made to Police Commissioner Howard Broad and the Independent Police Conduct Authority by Brash that the original investigation was conducted in a "cavalier fashion" and was the subject of political bias.
The review found that the investigation was competently carried out and agreed with its findings.
However, the review was critical of the lack of management over the timeliness of progress reports provided to Brash and that he had to wait too long for his copy of the final report.
Shortland says the findings of the review did not support the complaint that the investigation was conducted in a "cavalier fashion".
However, it was of the view that there had been a lack of urgency to complete the investigation once it was established that there were no threats to national and parliamentary security.
"The original investigation was conducted in accordance with police practice," he says.
"However, I acknowledge we could have been more timely with the closing stages of the investigation and final reports. But this in no way detracted from the professional conduct of the staff involved or the final outcome of the investigation."
Shortland says issues involving police management and administration of the case file had been addressed and guidelines for the receipt, evaluation and assessment, investigation and monitoring of complaints of a political nature were being developed."
There was no evidence of political bias.
Almost 200 interviews were conducted with parliamentary employees, including I&T, security, messengers, cleaners and contractors, along with a number of other people, to corroborate information gathered in the original investigation.
Although no suspect leads were identified, the interviews did provide evidence of unsatisfactory security on the third floor both in terms of access to the floor and offices and to individual computers. These afforded opportunities for access to a range of documents, both hard copy and electronic.
"Despite the number of staff and hours invested in the investigation and the review and examination of computers, it has not been possible to establish the source of the emails and other documentation that found there way into the public arena," says Shortland.
"I am fully satisfied that everything possible has been done to identify the source of the emails and this is now the end of the matter."
However, Key is not so convinced.
"There's no questions other people had access to the system -that's a statement of fact. There are contractors who have access to those old systems," he says.
Brash expresses thanks
Brash has expressed his thanks to police for the way they have handled the new investigation. Originally he has expressed disquiet over the way it was handled.
"The original Police investigation of the breach of security around my Parliamentary office lacked urgency, and gave every appearance of being treated as a matter of no consequence.
"Following my formal complaint to the Independent Police Conduct Authority in the middle of last year, the Police launched a thorough investigation, interviewing all the obvious potential suspects, some for the first time. Even though their inquiries have failed to identify the source of the leak, I certainly appreciate the effort they have put into this second investigation.
"At this stage, it appears unlikely that the person who stole emails from my office will ever be identified and I greatly regret that. However, I have moved on to new challenges and, though the report from the IPCA is still to come, I am willing to accept that there is nothing more that the Police can do," Brash says.