FLORENCE, Italy — Alan Friedman is Italy’s professional American. A former journalist with a baritone voice and perfect, if heavily accented, Italian, he has for decades provided the American perspective to Italians.

He hosted and produced Italian television shows, ran in elite circles, wrote the authorized biography of former Prime Minister Silvio Berlusconi and still contributes columns to the country’s most prestigious newspapers.

But for all his fame and influence in Italy, few had heard of Mr. Friedman in the United States until he helped land President Trump’s former campaign chairman, Paul Manafort, in jail.

Documents filed last month by the special counsel, Robert S. Mueller III, as part of the investigation into Russia’s influence campaign in the 2016 American presidential election, showed that Mr. Friedman worked closely with Mr. Manafort in creating the so-called Hapsburg Group.