The sources said Representative Mike Rogers, chairman of the House of Representatives Intelligence Committee, was talking about a plot hatched by Najibullah Zazi, an Afghan-born U.S. resident, when he said on Thursday that such surveillance had helped thwart a significant terrorist plot in recent years…

Miller said authorities traced the sender of the email to a suburb of Denver. At the time of Zazi’s arrest, U.S. authorities revealed that he had been tracked from Denver to New York, where, after a brief interlude during which U.S. investigators lost track of him, he was arrested by the FBI.