was among the leading German Muslims in Berlin. The son of a Jewish industrialist, and a homosexual, Marcus studied at the Friedrich-Wilhelms-Universität in Berlin in the first decade of the twentieth century. To support his family after financial reverses caused by World War I, he tutored foreign Muslim doctoral students in German. This led to his conversion to Islam, and for a dozen years, under the adopted name Hamid, he was the most important German in Berlin's mosque community. Nevertheless, he did not terminate his membership in the Jewish community, nor his ties to friends in the homosexual rights movement. The Nazis incarcerated Marcus in the Sachsenhausen concentration camp as a Jew in 1938, and he claimed to have remained there until a delegation led by his imam, Dr. Sheikh Muhammad Abdullah (1889-1956), gained his release. Abdullah