Born in New York on October 20 1918, Lochner grew up in Berlin; after studying in Chicago, he returned to Germany as a US soldier in 1945 after the end of the Nazi dictatorship. His firm knowledge of the German language enabled him to become chief interpreter for the US occupation forces in Western Germany, until he took a position as chief editor of the "Neue Zeitung" newspaper in Frankfurt in 1949.
Lochner also was head of the Radio in the American Sector, RIAS, a radio station supported by the US government in West Berlin during Kennedy's visit to West Germany, and also acted as Kennedy's interpreter, helping the president practice his speech on June 26 1963 and the key phrase "Ich bin ein Berliner" ("I am a Berliner"), for which he created the phonetic spelling "ish been oin bear-lee-ner".
Later in his life, Lochner worked in Vietnam and Washington, before retiring in Berlin. He died from a lung embolism on September 21 2003, and leaves three daughters and a son.