Three Government Communications Security Bureau agents refused to be interviewed by police investigating illegal spying into Kim Dotcom.
One of the agents attended a crucial initial briefing between police and the GCSB, and processed a request for information (RFI) from police. Documents released to Fairfax Media by police show the agent "declined" to be interviewed.
The papers also show that one GCSB agent changed his story during the course of the investigation.
The inquiry was sparked by Greens co-leader Russel Norman, who laid a complaint about illegal surveillance of internet mogul Dotcom and his piracy co-accused Bram van der Kolk.
In August police said they found one communication relating to Dotcom was illegally intercepted by GCSB agents. But because it was not done with "intent", police would not press criminal charges.
Dr Norman said police applied a " really terrible double standard" compared with an investigation into Bradley Ambrose, the cameraman at the centre of the teapot tapes scandal.
Police would only release an executive summary of the Operation Grey findings. It refers to a "conflict" between Detective Inspector Grant Wormald and GCSB staff about the crucial December 14 meeting.
Eventually police accepted Mr Wormald's account after viewing three court documents filed by GCSB - "each successive document softening their position" - and interviewing a GCSB agent.
GCSB eventually acknowledged Mr Wormald "may well have been right."
"There are two inferences that can be taken from this shift in position," the file says. "The first is that the GCSB member has not told the truth in order to protect his position and professional reputation...the second is that as he has became aware of systematic and institutional GCSB failings he has changed his position."
The investigators accepted he changed his account to reflect new information "he was becoming aware of."
The investigation concluded that although GCSB staff were "negligent" and incompetent" they did not intend to break the law.
The documents also note that 10 GCSB staff were interviewed, but three declined and one went overseas.
Dr Norman is not satisfied. "It is the same issue of the interception of private communications [as that when Mr Ambrose was investigated]. In that case they forced Vodafone to hand over text messages between Ambrose and his lawyer and the media...
"It's not weird, it's double standards."
Dr Norman has now laid a complaint with the Independent Police Conduct Authority.
A spokesman for police said: "Under the Bill of Rights Act, in any criminal investigation conducted in New Zealand, individuals have the right of silence and Police cannot compel any person to undergo an interview."
GCSB would not comment.
Yesterday Prime Minister John Key refused to confirm whether he had been briefed to expect leaks from US spy whistleblower Edward Snowden that would embarrass New Zealand.
- Fairfax Media
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