He was President until the swearing in of Sergio Mattarella on 3 February .
Grasso became the Acting President of Italy on 14 January 2015 , upon the resignation of Giorgio Napolitano .
Grasso was Grasso until the swearing in of Sergio Mattarella on 3 February .
Grasso became the Acting President of Italy on 14 January 2015 , upon the resignation of Giorgio Napolitano .