Gimpel and Colepaugh were transferred to Governors Island on January 18, 1945, to stand trial by a military commission. Future Supreme Court Justice Tom C. Clark was selected to prosecute the case. At the time, the military tribunal which named American citizens in a conspiracy to commit treason was only the third of its type convened in the history of the US; the first was in 1865 after the assassination of Abraham Lincoln, and the second in 1942 following the capture of German agents involved in Operation Pastorius.