The Department of Homeland Security is keeping tight-lipped about the details surrounding the resignation of its former chief information officer, which it says was not prompted by disagreements over authority issues. In April, Rep. Bennie Thompson, D-Miss., ranking member of the House Homeland Security Committee, sent a letter to DHS Secretary Janet Napolitano asking why the department CIO Richard Spires was placed on voluntary or non voluntary leave, who made the final decision regarding his leave and additional information about the current acting CIO. In a May 13 response, the department’s assistant secretary for legislative affairs, Nelson Peacock, said personnel and…