Sandro Mattioli is the author of the bestseller Germafia, in which he reports on the activities of Italian organised crime groups in Germany, Austria and Switzerland. The sectors he mentions include big financial institutions doing business with Mafia groups, as well as leading football teams. In this book, he also recounts his personal friendship with Luigi Bonaventura, a former 'Ndrangheta boss who has collaborated with law enforcement agencies for decades to combat the 'Ndrangheta. The book has had a significant influence on politicians and lawmakers.

Mattioli has been investigating Italian organised crime groups for almost twenty years and has published several documentaries aired by public TV networks, as well as revelations published by leading print magazines and a number of other books.

He also works as a speaker and consultant for film and TV productions, podcasts and other media. He regularly gives lectures and seminars on combating money laundering.

As the long-standing chairman of the anti-Mafia association Mafianeindanke, he campaigns for greater transparency and awareness of organised crime in Germany. The NGO has achieved notable successes in the fight against money laundering, for example in real estate.