Before the war, Kurt Gruber was a German miner from the Ruhr area.  He was an anti-fascist and a member of the Communist Party.  Before they were even in power, the Nazis shot his brother Karl on March 24, 1931.  When the Nazis took control of Germany in 1933 Gruber came under great danger from the regime, and he fled to Prague in 1935.  After the Nazi occupation of Czechoslovakia he managed to escape to Great Britain, and settled in Glasgow. There he again worked as a miner, became a member of the Scottish miners' union, and was very active in the Free Germany movement. In the summer of 1944, Kurt Gruber married Jessie Campbell. He also published a brochure titled I am a German Miner.

In 1944, the US Office of Strategic Services, the forefather of today’s Central Intelligence Agency, began recruiting Germans from the Free German Movement to be parachuted into Germany to serve as spies.  Their task was to transmit information about German troop movements and the political conditions in the country as the Allied Forces moved into Germany.  Kurt Gruber was among those who volunteered to serve in this capacity, and he joined the OSS as a spy.   Gruber was killed on March 20, 1945 when the aircraft carrying him to his parachute drop crashed in bad weather.  (This was the same plane crash that killed Sgt. Frederick Brunner who is also buried at the Ardennes American Cemetery.) Gruber was posthumously awarded the (civilian) Medal of Freedom.
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The information above is summarized from https://de.wikipedia.org/wiki/Kurt_Gruber_(Widerstandskämpfer) and http://wikivisually.com/lang-de/wiki/Kurt_Gruber_(Widerstandskämpfer)