On Saturday, I revealed in the newspaper De Tijd that HSBC, one of the biggest banks in the world, helped thousands of rich Belgians elude hundreds of millions of euros in taxes. The story was based on the records of 3,137 secret bank accounts belonging to 2,450 Belgian clients of HSBC Private Bank in Switzerland. The data also includes internal notes of Swiss bankers’ communications with these clients, exposing how the bankers helped clients set up offshore companies and maintain a veil of secrecy over their finances.

My investigation started with a simple question: How can I expose the dubious practices of Swiss bankers? I could talk to witnesses, but that would only expose the tip if the iceberg. But how could I trace the numerous offshore companies that their rich clients use to avoid taxes and remain anonymous? It’s impossible without the help of an insider. Even if I searched all the available databases of companies in Panama, the British Virgin Islands, and other tax havens, I would never be able to unmask who hides behind the bogus directors.

But when I heard three years ago that Hervé Falciani, a former employee of HSBC Private Bank in Switzerland, had copied numerous data of the bank, I knew I had to get my hands on the Belgian data. But how? Well, I can’t reveal how I finally obtained the data, only a few weeks ago. But let’s say it was a long road to get there.

From the start I wrote about every new step in the fiscal and criminal investigations in Belgium resulting from the HSBC leak. The Belgian authorities had obtained Falciani's data from the French, who had initially recieved it. In 2011, I gathered the names of 170 Antwerp diamond dealers that were HSBC clients in Geneva. The assembled list of names was an eye opener. Almost every important diamond dealer, the heads of specialized exchanges called diamond bourses, and officials in other key institutions in Antwerp, the diamond capital of the world, were suspected of tax fraud.

I continued my investigation and spoke with lawyers, bankers, magistrates, police investigators, fiscal investigators, politicians, exposed HSBC clients, and others. This hard work paid off when a few weeks ago I received the entire list of 2,450 HSBC clients in Geneva, and their 3,137 bank files. I saw the names of nobility, a minister of state, CEOs of big Belgian companies, big lawyers, board members of Belgian banks, and a famous Belgian entertainer.

I was able to go beyond simply naming names, though, thanks to the rich trove of internal file notes. The communications between the bankers and their Belgian clients exposed the tactics they used to keep the clients’ secrets, helping them hide money and transactions from tax authorities. “Client is terrified that she will be exposed to the Belgian fiscal authorities,” one note says.

The notes show how the bankers encouraged their clients to use anonymous companies in Panama and other tax havens, made discrete visits to clients’ homes in Belgium, held secret meetings in hotels in Brussels and Antwerp and used code language when talking on the phone. “Client can’t be called,” one note explains. “He calls us, then uses name of a football player and asks us the price of the caviar, meaning the total amount of his assets.”

It took three years of investigation, while continuing to work on other stories for our newspaper, De Tijd, to finally got me to this point. But it doesn’t stop here. I will continue to investigate.

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