Alleged terrorist known but not thought a threat

WASHINGTON — A popping noise, an odor, then flames.

What sounded like firecrackers was the climax of a failed attempt by a suspected terrorist to blow up a U.S. jetliner on Christmas Day.

Northwest Flight 253 passengers and law enforcement officials described the events surrounding the Christmas Day attack:

_On Thursday, Dec. 24, Umar Farouk Abdulmutallab, 23, began traveling from Nigeria to Amsterdam and then on to Detroit with an explosive device attached to his body.

Part of the device contained PETN, or pentaerythritol, and was hidden in a condom or condom-like bag just below his torso. PETN is the same material convicted shoe bomber Richard Reid used when he tried to destroy a trans-Atlantic flight in 2001 with explosives hidden in his shoes. Abdulmutallab also had a syringe filled with liquid.

_On Friday, Dec. 25, as the plane approached Detroit, Abdulmutallab went to the bathroom for 20 minutes. When he returned to his seat, he complained of an upset stomach and covered himself with a blanket.

Passengers heard a popping noise, similar to a firecracker. They smelled an odor, and some passengers saw Abdulmutallab's pant leg and the wall of the airplane on fire. Blankets and fire extinguishers were used to quell the flames. They restrained Abdulmutallab, who later told a flight attendant he had an "explosive device" in his pocket. He was seen holding a partially melted syringe.

The airplane landed in Detroit a short time later, and Abdulmutallab was arrested. He was taken to a hospital for treatment of burns.

_On Saturday, Dec. 26, federal officials charged Abdulmutallab with trying to destroy the airplane. A conviction on the charge could bring him up to 20 years in prison and a $250,000 fine.

A federal judge read Abdulmutallab the charges in a conference room at the University of Michigan Medical Center in Ann Arbor, Mich., where the former London university student was being treated for burns. Abdulmutallab smiled as he was wheeled into the room. His left thumb and right wrist were bandaged and part of the skin on the thumb was burned off.

_On Sunday, Dec. 27, Abdulmutallab was released from the hospital and taken to a federal prison 50 miles outside Detroit.

Obama administration officials said there would be a review of security and watch list procedures.

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Abdulmutallab claimed to have received training and instructions from al-Qaida operatives in Yemen, law enforcement officials said. He was also believed to have had Internet contact with militant Islamic radicals.

While intelligence officials said they took seriously Abdulmutallab's claims that the plot originated with al-Qaida's network inside Yemen, several added that they had to yet to see independent confirmation. The officials spoke on condition of anonymity because the investigation is incomplete.

Four weeks ago, Abdulmutallab's father told the U.S. Embassy in Abuja, Nigeria, that he was concerned about his son's growing hard-line Islamic religious beliefs and possible affiliations with fundamentalist groups, according to a U.S. government official who spoke on condition of anonymity because he was not authorized to discuss the investigation. This information was shared with U.S. intelligence officials, and Abdulmutallab's name was added to a vast government database of people with suspected or known terror associations.

Abdulmutallab came to the attention of intelligence officials months earlier, though, according to a U.S. government official involved in the investigation, who spoke on condition of anonymity because it is ongoing.

Still, none of the information the government had on Abdulmutallab rose to the level of putting him on the official terror watch list or no-fly list. Abdulmutallab received a valid U.S. visa in June 2008 that is good through 2010.

His is one of about 550,000 names in the Terrorist Identities Datamart Environment database, known as TIDE, which is maintained by the U.S. National Counterterrorism Center and was created in response to the Sept. 11, 2001, terrorist attacks. Intelligence officials said they lacked enough information to place him in the 400,000-person terror watch list, the list of about 14,000 names of people who need additional screening before they fly or on the no-fly list of fewer than 4,000 people who should be blocked from air travel.

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Associated Press writers Larry Margasak, Pamela Hess, Matthew Lee and Lolita Baldor in Washington, Philip Elliott in Honolulu and Ed White in Detroit contributed to this report.