Greg Dyke, the director general of the British Broadcasting Corporation, has stepped down in the wake of a damning report by a UK judge involving the death of a BBC source who had accused the Blair government of “sexing up” a dossier on the threat posed by Iraq. The suicide of Dr. David Kelly, who anonymously provided information to a BBC reporter before being revealed by another media outlet, led to six weeks of hearings before Lord Hutton, who also cleared the Blair government of all wrongdoing in his report.