Tax evasion is a widespread phenomenon confirmed by numerous European and American reports. To contrast it, governments already adopt software solutions that support tax inspectors in their investigations. However, the currently existing systems do not normally take advantage of the constant stream of data published on the Web. Instead, the ASIA project aims to prove the effectiveness of combining this kind of open source information with official data contained in Public Administration archives to fight tax evasion. Our prototype platform deals with two cases of investigation, people and businesses. Public officers have been involved throughout the project, and took part in a preliminary test phase which showed very promising results.