Following his election in 2005, strong controversy erupted when it was revealed by the magazine Der Spiegel that he had worked for the Stasi (the East German secret police) from 1985 to 1990.
Po jeho zvolení v roce 2005 vypukla silná kontroverze, když magazín Der Spiegel odhalil, že Heilmann v letech 1985 až 1990 pracoval pro Stasi (východoněmeckou tajnou službu).