Lived in Stuttgart. Sugar producer - Süddeutsche Zuckerfabriek, Mannheim - with his half-brother Josef. He moved to Milan, Italy and in 1939 emigrated to Winnipeg, Canada. He later moved to New York.
According to The American Journal of International Law, Vol. 53, No. 4. (Oct., 1959), pp. 944-958:
"Albert and his two older brothers were included in the father's 1894 naturalization in Wurttemberg. Albert lived in Germany until 1937, apparently unaware of his father's one-time American citizenship until after the Nazis took power in 1933. Between 1933 and 1939 Albert and his brother Eugene contacted several American Consulates in Europe, and the American Embassy in Paris, seeking to find out whether they might have preserved American citizenship through their father, but received negative or ambiguous information."
"...... the Immigration and Naturalization Service on February 24, 1942, ordered that Flegenheimer be given the status of an American national. The Department of State refused him a passport to travel to Europe on May 14, 1946; but granted him an American passport October 24, 1946."
A certificate of nationality was issued to him July 10, 1952.