On the Trail of Il Duce.

I had come to Phoenix, among the Arizona saguaros and 6,000 miles from home, to look for one of my country's best-kept secrets. And here he is, watering the flowers outside his motor home, a tall and handsome man of 61, living on unemployment benefits. He greets me with a sad smile full of dignity. Ferdinando Petacci is the last living heir of Clara Petacci, who in April 1945 chose to be shot together with her lover, Benito Mussolini, the Italian dictator. Their corpses were then hung upside down in a Milan square.

In Italy, only Gypsies live in motor homes. But in America, going on the road, losing oneself, is commonplace. This man could be a millionaire, if the Italian government gave him back his aunt's diaries and the thousands of letters Mussolini sent her during their 12-year romance. Long ago the minders of state secrets told him he could have them in 50 years. Then in 1995 they invented a new law that would keep them out of his (and the public's) hands until 2015. He wonders, "Why are they so afraid?"

Ferdinando was just 3, fleeing with all his family in an Alfa Romeo along Lake Como, when the communist partisans caught them. His father, one of Mussolini's entourage, was executed on the spot, along with his aunt who asked to share Il Duce's fate. His mother was raped for days on end; his older brother never overcame the shock and died young. Ferdinando himself made a brilliant career as an executive in a French multinational in Europe and South America. He moved to the United States with his sons, divorced, set up a catering service in California, then slipped onto a downward path. He lost his last job in a restaurant in Colorado a few months ago.

Ferdinando's trailer is equipped with computer, phone, fax, e-mail. He is in constant contact with his Italian lawyer. Aunt Clara became Mussolini's political ...