Because the German agents were captured in civilian clothes (though they had landed in uniforms), they were tried by a military tribunal in Washington D.C., with six of them sentenced to death for spying. President Franklin D. Roosevelt approved the sentences. The constitutionality of military tribunals was upheld by the U.S. Supreme Court in "Ex parte Quirin" on July 31, and the six men were executed by electrocution at the D.C. jail on August 8. Dasch and Burger were given thirty-year prison sentences because they had turned themselves in to the FBI and provided information about the others. Both were released in 1948 and deported to Germany. Dasch (aka George Davis), who had been a longtime American resident before the war, suffered a difficult life in Germany after his return from U.S. custody because he had betrayed his comrades to the U.S. authorities. As a condition of his deportation, he was not permitted to return to the United States, even though he spent many years writing letters to prominent American authorities (J. Edgar Hoover, President Eisenhower, etc.) seeking permission to return. He eventually moved to Switzerland and wrote a book, titled "Eight Spies Against America".