In fact, he's been anything but.
"He wouldn't even admit he had been in Afghanistan," one official said.
Defense Secretary Donald Rumsfeld, on a trip to help lower the temperature in the dispute between India and Pakistan, said earlier that the United States didn't necessarily want to prosecute the suspect, just find out "what he knows." That might not prove so easy.
U.S. investigators consider the suspect, Padilla, a particularly hard nut to crack with a lengthy past of bad luck and criminal activity.
Padilla, who has called himself Abdullah al Muhajir for more than a decade, had been in Justice Department custody since he was arrested on May 8. Last Sunday, U.S. investigators washed their hands of him and turned him over to the Defense Department as an "enemy combatant." The Defense Department has put him in the Navy brig at Charleston, S.C.
Padilla's hard-nosed recalcitrance is in contrast to the position taken by Abu Zabaydah, formerly operational chief of al Qaida for terrorist mastermind Osama bin Laden.
Zabaydah was wounded and captured in a firefight with Pakistani police, with help from the FBI, on March 28. Almost immediately, he was turned over to U.S. custody. The Defense Department has him stashed, along with hundreds of other al Qaida and Taliban fighters, at the U.S. Naval Base in Guantanamo Bay, Cuba.
Zabaydah has been talking, though U.S. investigators sometimes question the accuracy of what he is saying. He has been the source of several generalized alerts in the United States -- for instance, telling his questioners that top al Qaida members were considering an attack on a U.S. bank.
He is also believed to be one of the sources who put U.S. investigators onto Padilla's trail.
Born in New York City in 1970, Padilla moved with his family to Chicago when he was 5. Though authorities refuse to describe his alleged criminal activity in that city -- juvenile records are sealed -- many officials describe him as "troubled."
He was arrested in Florida in 1991 on a handgun charge and spent part of a year in state prison. It was there that he apparently converted to Islam and took the name al Muhajir.
Padilla had been out of the country since 1998. U.S. officials say they have proof that he spent much of that time in Afghanistan and Pakistan, training at al Qaida camps in both countries. His specialty was wiring bombs, and he did some research on radiological material, investigators said.
At a Monday news conference announcing Padilla's capture, FBI Director Robert Mueller said the conspiracy to bring al Qaida terror once again to American soil was in its very early stages, and there was no evidence that Padilla had assembled any part of a dirty bomb.
"It (the plot) was in the discussion stage," Mueller said. "It did not go much beyond the discussion stage."
A number of media reports said Padilla would have targeted Washington if he had carried out the plot, but Mueller and Deputy Defense Secretary Paul Wolfowitz said the plotters had not decided on a final target.
Meanwhile, a controversy is developing over the terms of Padilla's incarceration. As an "enemy combatant," he could be held indefinitely by the Defense Department without being brought to trial.
As a U.S. citizen in Justice Department custody -- in fact, he was held as a "material witness" -- Padilla had the right to a lawyer. That court-appointed lawyer has filed suit in federal court in New York challenging Padilla's indefinite detention. All documents in the suit are under seal.
Notable deaths of 2014 [PHOTOS]