Senator Charles Grassley and Congressman Darrell Issa have shifted the focus of their continuing probe into Operation Fast and Furious to the FBI, and on Thursday sent a letter to Director Robert Mueller, seeking specific information about the investigation. The two Republicans, who have been digging into the scandal for months, immediately made it clear to Mueller they are weary, and wary, of the lack of cooperation their investigation has received. “The murder of Border Patrol Agent Brian Terry on December 14, 2010, is what motivated brave law enforcement agents from the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)...