The diary of Nazi leader Alfred Rosenberg disappeared without a trace after his trial in Nuremberg. Sixty-four years later it's been recovered in upstate New York.

In an early assessment of its contents, the U.S. government and the United States Holocaust Museum say it will shed new light on the inner workings of the Nazi high command. "The diary will be an important source of information to historians that complements and in part contradicts already known documentation," a Holocaust Museum statement said in an assessment of the find. Further details will be revealed today at a press conference in Wilmington, Delaware.

Who was Rosenberg? Charles Fenyvesi reports.

Alfred Rosenberg was a misfit among misfits. He viewed himself as an intellectual, and—measured against Nazi bigwigs like Adolf Hitler, Rudolf Hess, and Hermann Goering—perhaps he was. But that is faint praise. Rosenberg wrote a best-selling book, The Myth of the Twentieth Century, that became the bible of the Nazi movement. Its translations sold well in many European countries, encouraging anti-Semitism. Its elephantine sentences and complex, pseudo-scientific "facts" and semi-mystical tenets were hard to follow, though the text bristled with the hatred of Jews, Russians, Poles, Czechs, and others he condemned as "subhuman." According to the architect Albert Speer, who became the Minister of Armaments and War Production for the Third Reich, Hitler called the book "stuff that nobody could understand." William L. Shirer, the great American historian of the Nazi era who knew Rosenberg, called his mind "muddled."

Ironically the architect of the Nazi theory of German racial superiority was considered by many Germans a foreigner, born in Estonia, then part of the Russian empire. He chose to study at Moscow University and was proud of his diploma in architecture. His enemies in the Nazi party spread rumors that he was not a Baltic German, as he claimed, and that he had Russian ancestry—or he was of Estonian stock. The rumors went as far as suggesting that while a student in Russia witnessing the Bolshevik Revolution, he flirted with the notion of joining it. But shortly after he migrated to Germany, he became one of the first members of Hitler's party.

In 1923, following an unsuccessful coup d'etat, Hitler was imprisoned and named Rosenberg the head of the Nazi party until his release. But Hitler told his inner circle that Rosenberg was lazy and unfit to lead. Rosenberg was a poor public speaker who lacked charisma and friends in the Nazi party. Nonetheless, in 1934 Hitler put Rosenberg in charge of the spiritual and philosophical education of the Nazi party. He promoted the idea of the German Reich's eastern expansion and advocated a merciless war on the Slavs. He invented the notion of "Lebensraum"—living space—and argued that it was not only a necessity, but also a moral imperative for Germans, the "master race," to conquer territories where inferior races had failed to create a high culture. After Germany attacked the Soviet Union, Rosenberg became Reich minister for the occupied territories.