One senior State Department official did not dispute the possibility -- but could not confirm -- that the State Department may not have realized in November that the individual already held a U.S. visa but noted that someone else in the government, such as security or counterterrorism agencies, would also have had access to that information.
State Department spokesman Ian Kelley said that despite the information provided by the suspect's father, the counterterrorism community determined there was "insufficient" evidence to warrant pulling his U.S. visa. This was not Abdulmutallab's first U.S. visa and he had traveled to the United States under a previous visa.
Abdulmutallab has warned that there are more men like him but U.S. officials have no evidence that the incident was one in a wave of planned attacks. Officials will take Abdulmutallab's DNA sample later today, a fairly routine procedure in a case like this.
A hearing was scheduled for Abdulmutallab today, but a spokesperson for federal prosecutors said it was canceled. There will be a preliminary hearing Jan. 8.
Abdulmutallab's mission was already in full effect the moment he boarded the plane in Amsterdam, according to ABC News sources.
He had a visa to enter the United States despite his being on the terror watch list. And he paid $3,000 in cash to purchase his ticket, checking no luggage.
Once on the plane, Abdulmutallab walked to seat 19A, next to the wing, and above the fuel tank, apparently choosing the location to maximize the chances of bringing the plane down.
He wanted to blow up the plane over the airport so investigators would find evidence that it was terrorism, the sources said. He went into action just before landing, going to the bathroom and staying there for 20 minutes.
He came back to his seat complaining of a stomachache and covered himself with a blanket. Soon, passengers started noticing fire emitting from his pants.
"There was a bang," passenger Elias Fawaz recalled. "Sounded at first like a balloon went off."
As Abdulmutallab was trying to detonate the bomb in his lap, the wall of the plane caught fire, passengers said.
"I'm sitting here, the flames were leaping up at least this high," said Daniel Huisinga, putting his hands above his head.
The Nigerian national had packed 80 grams of the explosive pentaerythritol tetranitrate, or PETN, the same kind that shoe-bomber Richard Reid used, but even more powerful. But the explosives sewn into Abdulmutallab's underwear failed to ignite, and passengers subdued Abdulmutallab.
One passenger recalled the flight attendant's emotional announcement when the nightmare was over.
"He was just shaking and crying in the speaker, saying, 'The situation is taken care of, the fire is out,'" passenger Richelle Keepman said.
Napolitano said the administration is beginning to deploy new technology at airports.
"There will be lessons learned that we deal with and fix. And that process is ongoing, and as you might imagine, it's ongoing at lightning speed," she said on "GMA." "We are going to get to the bottom of this."
Some experts said while the United States already has new technology to combat this issue, it's not available nationwide, and it's very expensive and considered by some to be intrusive.