Attorney General John Ashcroft (AP)

"I am pleased to announce today a significant step forward in the War on Terrorism. We have captured a known terrorist who was exploring a plan to build and explode a radiological device, or 'dirty bomb' in the United States." —Attorney General John Ashcroft. June 10, 2002.

It was, to be certain, a stunning announcement by the attorney general, made all the more significant by the fact that John Ashcroft had carved time out of his schedule during a trip to Moscow to make it.

After months of vague warnings about potential attacks on American targets by shadowy terrorists linked — directly or indirectly — to Osama Bin Laden's al Qaeda network, U.S, authorities had something tangible to show to the American people. They could now, Ashcroft told a group of international reporters, put a face on the threat. And it was an American face, the face of a Puerto Rican kid born in New York City who had drifted from New York to Chicago to Florida, always with the law close at his heels, a young man who, they said, embraced Islam in prison, and embraced terrorism during several trips to Pakistan.

His plans were awful and terrifying, the attorney general said. "From information available to the United States government, we know that Abdullah al Muhajir is an al Qaeda operative."

"Let me be clear," the attorney general said. "We know from multiple independent and corroborating sources that Abdullah al Muhajir was closely associated with al Qaeda and that as an al Qaeda operative he was involved in planning future terrorist attacks on innocent American civilians in the United States."

With his apprehension — first as a material witness in the probe into the terrorist attacks on September 11, and later as a prisoner of war — "we have disrupted an unfolding terrorist plot," Ashcroft said. "Because of close cooperation among the FBI, the CIA, Defense Department and other federal agencies, we were able to thwart this terrorist."

Days later, President George W. Bush, speaking to reporters, praised the arrest, and the decision he had made to declare the 31-year-old Padilla an enemy, not entitled to the protection criminals enjoy under the U.S. Constitution. "This guy Padilla is a bad guy," the president said. "He's where he needs to be, detained."

In fact, the government took the threat Padilla posed so seriously that it emptied out an entire wing of the brig at the Charleston Naval Air Station to make room for the accused terrorist and the small army of Navy men assigned to guard him.

Within two months, however, the government officials, speaking on condition of anonymity, began to privately question just how big a fish they had caught with Padilla.

Newsweek reported August 13 that a rigorous investigation by the FBI had turned up no evidence that Padilla had begun any preparations for an attack on his homeland and little evidence to support the government's contention that he received significant support from al Qaeda officials. Authorities told the magazine that they had failed to find or identify any of Padilla's alleged contacts in the U.S., and one intelligence official reportedly told the magazine that the whole idea that Padilla was the linchpin in a plot to wreak havoc on an American city with a dirty bomb was "blown out of all proportion."

Abu Zabaydah

Still, authorities had some evidence linking Padilla to the terrorist network that had attacked America. Investigators had found a photograph of Padilla in an al Qaeda safe house in Pakistan and found lingering evidence on a hard drive on a computer in the house that showed that someone, most likely Padilla, had been cruising the Internet searching for labs and universities in the U.S. that might unwittingly be able to provide the low-grade radioactive waste needed to manufacture a dirty bomb. Then, of course, there were the statements investigators had been given by Abu Zabaydah, a high-ranking al Qaeda chief who was picked up last fall after a gun battle in Pakistan.

Zabaydah had not always been the most reliable source for American intelligence. Several of the wrenching warnings issued late last year by the American government originated with information provided by Zabaydah. And it was Zabaydah who first led American investigators to Padilla. The former al Qaeda training chief told his captors that he had been approached by a young American — he never named him — and two accomplices interested in discussing a plot to use a dirty bomb within the borders of the United States. Later, authorities unearthed two more witnesses against Padilla, though government officials admitted in court papers that they had questions about their own witnesses' reliability.

All the same, the evidence, authorities said, pointed toward Padilla. It was circumstantial and hardly strong enough for the Justice Department to bring charges against him. But that, as it turned out, didn't really matter.