The Direction Générale Des Finances spent a year quietly looking into Google's tax affairs in the country before launching a surprise raid on the company's Paris offices at 5 a.m. local time on May 24. France may now try to claim back as much as €1.6 billion in what it says are unpaid taxes from Google.

The raid has apparently been a year in the making and involved 100 investigators. Financial prosecutor Éliane Houlette gave an interview to Europe 1 about how they kept it a secret. (We first saw the interview translated from French over on TechCrunch.)

So how did they manage it? The 100-strong team worked almost entirely offline. "We've worked offline on this investigation for nearly a year," Houlette said. "We used one computer, but only as a word processor."

The investigators also didn't even refer to Google by name, instead giving it a code name to obscure what they were working on. "In order to protect this secret," Houlette said, "we decided that we would give another name to Google and never pronounce Google's name — Tulip."