The "spooks" at the centre of the latest Dotcom scandal may have intercepted communications by camping out near the German millionaire's house and deploying specialist snooping equipment.
Author and journalist Nicky Hager, whose 1996 book Secret Power lifted the lid on the shadowy Government Communications Security Bureau, said the agency's spies were "not spies in the normal sense".
"They're technicians . . . and they are the people who do a technical job."
Hager's book traced New Zealand's involvement in the global Echelon network, which spies on communications, including emails and phone calls. He interviewed a number of GCSB staff for the book.
The GCSB's involvement in the Dotcom case has raised questions about how and what information was collected on the internet entrepreneur.
Hager said the fact the GCSB operated without warrants limited its options, because any snooping which necessitated planting a device would require one. "They can legally go out and listen to the airwaves, because that's not planting a device.
"So they could theoretically sit on a hill and pick up signals. Those signals intelligence officers are very good . . . they pick up all the local radio signals so basically they would be picking up his mobile-phone traffic."
The other way they could spy on Dotcom was through the Waihopai listening station, which is part of the Echelon network. "They'd actually just plug in his email address, his name, his company name whatever and see what comes off it."
Overseas, drones - or aeroplanes - might also be used.
"But in New Zealand I don't think they would do this. They would just have someone camping nearby, or sitting between there and the next mobile tower."
- The Dominion Post