The Security Intelligence Service is believed to have been monitoring a former MP's foray into the world of top-secret spy planes.
Trevor Rogers is understood to have raised suspicions after boasting about his plans to develop a full-size unmanned helicopter for civil and military use.
Mr Rogers, who was an Auckland city councillor from 1977 to 1989 and a National Party MP from 1990 to 1996, refused to comment.
But a Herald investigation has revealed he talked openly about the helicopter's "stealth" capabilities, distributing photographs of a prototype carrying what appeared to be missiles.
In 2009, a year after the collapse of his company, TGR Helicorp, he issued a press release saying "the programme is far from becoming history".
Documents and emails on his computers appear to show he wanted to sell the technology to Pakistan, India, France, Italy, Vietnam, Georgia, Azerbaijan, Jordan, Singapore, China, the United States and South Korea.
According to a friend, Mr Rogers also said he travelled to Israel "looking for bombs and bullets and stuff".
When the Ministry of Foreign Affairs and Trade refused to give him permission to export the technology, he made plans to move to Switzerland.
Court documents reveal Mr Rogers requested a copy of his personal file from the SIS in May 2009. He believed the SIS was investigating his activities in Europe and wrote to its director insisting that "what I do now in the rest of the world is absolutely no business of New Zealand".
He described the SIS investigation as "a slap in the face" and "the last straw".
The documents also reveal that Ernst & Young partner Gareth Morgan - not the economist of the same name - appeared to be acting as a sales agent for Mr Rogers.
His claims that one of his helicopters could be used for rescues on Mt Everest attracted the attention of Lady Louise Fiennes, wife of British explorer Sir Ranulph Fiennes.
But the project collapsed three years ago when investors pulled out.
Since then receivers have been trying to trying to track down the company's assets, including technical drawings said to be worth "millions and millions of dollars".
Mr Rogers insists he has destroyed them. But a High Court judge has accused him of lying, and this year jailed him twice for contempt of court. His wife was also jailed.