Prosecutors in Genoa Wednesday said Giuliano Ibrahim Delnevo, 24, allegedly recruited one Italian Muslim convert and three North Africans with online sermons and a blog, ANSA of Rome reported.
The five men were being investigated for terrorism, ANSA said.
When reports came in Tuesday Delnevo had been killed fighting alongside rebel extremists in Syria, Italians were shocked to learn of his case, ANSA said. Delnevo was a student from Genoa, born to parents with no known links to Islam.
Delnevo converted to Islam in 2008, took the name Ibrahim, and posted Koranic passages on his Facebook page. He also posted a photograph of Abdullah Yusuf Azzam, the "Father of Global Jihad" who was Osama bin Laden's inspiration in taking up fundamentalist offensive jihadism, ANSA said.
"We are aware that someone who leaves Italy to fight in Syria is a phenomenon that needs to be monitored," Italian Defense Minister Mario Mauro said, adding the military was keeping track of Italians heading off to fight in Syria.
Between 45 and 50 people, including a woman, are believed to have left Italy to join the rebel groups in Syria, the group Communities of the Arab World in Italy said.