Commissioner Mattarollo was a founding member until his death in June 2014. He acted as Consultant of the Secretariat of Human Rights of the Ministry of Justice of Argentine. Formerly, he served as Sub-Secretary on Promotion and Protection of Human Rights of the Secretariat from 2005 to 2007 and as Head of the Cabinet of the Secretariat since 2003. .

Rodolfo Mattarollo studied law at the National University of Buenos Aires and hold a Diploma of Specialized Superior Studies on Political, Administrative and Social Organisation of the University of Paris I Pantheon-Sorbonne. In his academic career, Mattarollo has been lecturing as a professor on International Law at the University of Lomas de Zamora and at the Institute for Latin-American Integration of the University of La Plata. He was also visiting professor at the University V (René Descartes) of Paris. .

Mattarollo was appointed as the Coordinator of the Commission of UNASUR which investigated the events in Pando, Bolivia, in September 2008. In 2001, he was in charge of the Human Rights Section of the UN Mission in Sierra Leona (UNAMSIL). From 1996 to 2000 he acted as Deputy Executive Director and Head of Judicial Affairs and Institution Building of the International Civilian Mission of the OAS and UN in Haiti (MICIVIH). From 1993 to 1995, he was International Judicial Consultant in the Office of Special State Attorney of the Transitional Government of Ethiopia. .

Mattarollo was a member of the Council of the Presidency of the American Association of Jurists and honorary member of the Institute of Judicial Studies de El Salvador. He was also a member of the Council of the Presidency of the Permanent Assembly of Human Rights.