The country's most senior detective Rodney Drew today told the Labour Party that "there is no evidence of criminal offending".
"While the matter may raise privacy and ethical issues, these are not the domain of criminal law."
It's almost a year since details of the 2011 intrusion were described by journalist Nicky Hager in the controversial pre-election book Dirty Politics.
Hager wrote how Whaleoil blogger Cameron Slater conspired with a staff member in the Prime Minister's office, Jason Ede, to access Labour Party information through a hole in its website. He reported how Ede had avoided being identified by using a "dynamic IP address," which meant efforts to track him failed.
The details revealed in the book led to a multi-layered complaint by the Labour Party on the website intrusion and other claims made in the book. The other matters were dismissed by police last year. The reason, in a letter from Mr Drew, was that the "only evidence being relied on was contents of Mr Hagar's (sic) book and the entities and persons named did not want to pursue any action".
The letter from Mr Drew spelled from Mr Hager's name wrong and the name of the Labour Party general secretary Tim Barnett.
Mr Barnett - "Barnnet", according to police - said the police conclusions were "unbelievable". He said the party was considering further action.
He said compared to the effort being put into investigating Slater, it did not compare to the energy put into investigating Hager.
"I would expect to see a level of energy from the police that was equitable and we certainly haven't seen that in the treatment of us."
Two government inquiries into matters raised in Dirty Politics found evidence given by Slater could not be relied on - and that he had overstated his contacts and influence.
Hager is awaiting a High Court judgment on whether he can claim journalistic source protection in relation to the anonymous individual known as Rawshark who claimed to have hacked material from Slater's computer system. It followed a complaint by Slater and a police raid on Hager's house searching for information leading to the hacker's identity.
Police had previously dismissed a complaint by Matthew Blomfield that Slater had illegally accessed a computer hard drive to get emails and personal information used for blogposts. Blomfield has since taken defamation action against Slater over the posts.
Ongoing fallout from Dirty Politics saw The Standard website recently lay a complaint with police alleging Slater had attempted to hire a hacker to access the left-wing blog.
Slater - who did not wish to comment - has denied any wrongdoing.
