The former bank worker was also fined 3,500 francs ($3,727) after he confessed to having stolen confidential client data before selling it on to German officials.

The events go back to 2007, when the ex-Credit Suisse worker began pilfering confidential data “to kill time, out of passion and historical interest.”

One day, he accidentally left his briefcase at the gym where he worked out. An Austrian IT specialist, who also used the fitness centre, found the case and looked inside.

There he discovered some compromising handwritten notes from the defendant and, recognizing the potential benefits, made the defendant an offer.

The Austrian then contacted German fiscal authorities. With the help of the Credit Suisse employee, he delivered confidential data on up to 2,500 account holders in Switzerland with bank deposits totalling around 2 billion francs ($2.13 billion).

In exchange, the Austrian man received €2.5 million ($2.25 million), while the defendant took a cut of €320,000 ($417,000), the Tribune de Genève reports.

After his arrest in September 2010, the Austrian hanged himself in his prison cell in Bern. The defendant was detained at his girlfriend’s home in the Czech Republic.

Credit Suisse said it was glad the thief had been convicted. The Swiss bank paid a fine in September of €150 million ($185 million) to end the German investigation into tax evasion sparked by the data theft.