WASHINGTON -- In the anxious months after the Sept. 11 attacks, the National Security Agency began sending a steady stream of telephone numbers, e-mail addresses and names to the FBI in search of terrorists. The stream soon became a flood, requiring hundreds of agents to check out thousands of tips a month.
But virtually all of them, according to current and former officials, led to dead ends or innocent Americans.
FBI officials repeatedly complained to the spy agency - which was collecting much of the data by eavesdropping on some Americans' international communications and conducting computer searches of foreign-related phone and Internet traffic - that the unfiltered information was swamping investigators.
Some FBI officials and prosecutors also thought the checks, which sometimes involved interviews by agents, were pointless intrusions on Americans' privacy.
As the bureau was running down those leads, its director, Robert S. Mueller III, raised concerns about the legal rationale for the eavesdropping program, which did not seek court warrants, according to one government official.
Mueller asked senior Bush administration officials about "whether the program had a proper legal foundation," but ultimately he deferred to Justice Department legal opinions, the official said.
President Bush has characterized the eavesdropping program, which focused on the international communications of some Americans and others in the United States, as a "vital tool" against terrorism.
Vice President Dick Cheney has said it has saved "thousands of lives."
But the results of the program looked very different to some officials charged with tracking terrorism in the United States. More than a dozen current and former law enforcement and counterterrorism officials, including some in the small circle who knew of the secret eavesdropping program and how it played out at the FBI, said the torrent of tips led them to few potential terrorists inside the country they did not know of from other sources and diverted agents from counterterrorism work they viewed as more productive.
"We'd chase a number, find it's a schoolteacher with no indication they've ever been involved in international terrorism - case closed," said one former FBI official, who was aware of the program and the data it generated for the bureau. "After you get a thousand numbers and not one is turning up anything, you get some frustration."
