(CNN) -- Authorities on Sunday focused their investigation of the botched Christmas terror attack on how a lone traveler allegedly smuggled explosives aboard a Northwest Airlines flight and who might have helped him.
Umar Farouk Abdulmutallab, 23, a Nigerian citizen with a multiple entry visa to the United States, was charged in a federal criminal complaint with attempting to destroy the plane on Friday -- Christmas Day -- on its final approach to Michigan's Detroit Metropolitan Airport, and placing a destructive device on the aircraft.
President Barack Obama ordered reviews of how the suspect boarded a U.S.-bound flight with explosives and why a person listed last month on a broad watch list of 550,000 potential terror threats avoided extra scrutiny, White House Press Secretary Robert Gibbs said Sunday.
Obama, on vacation in Hawaii, is receiving regular briefings from his national security staff on the Christmas Day incident, Gibbs said in interviews on the NBC program "Meet the Press" and the ABC program "This Week."
Homeland Security Secretary Janet Napolitano told CNN's "State of the Union" there was no indication so far that the failed attack was part of a larger international terror plot. Asked about a possible connection to al Qaeda, Napolitano answered that investigations were continuing.
Despite a possible tragedy, Napolitano said the response system worked as passengers and crew subdued the suspect while authorities notified other flights in the air of the situation and kept the air transport system operating.
Security screening has been increased in the wake of the incident, with different procedures at different airports to prevent predictability, Napolitano said.
"While we continue to investigate the source of this incident, the traveling public should be very confident of what we're doing now," she said.
However, some members of Congress questioned how the incident could have happened.
"We ought to, in our age, be able to put 500,000 names on a computer and have everybody who's trying to come to the U.S. go through that list," Sen. Joe Lieberman, a Connecticut independent who sits with the Democratic caucus, said on "FOX News Sunday."
Republican Rep. Peter King of New York told the CBS program "Face the Nation" that the case appeared to be "a failure of the system."
"So let's honestly address that and admit the system did not work and find ways that we can move people off that 500,000 list on to at least a secondary screening list," King said.
Both King and Lieberman called for using full body scanners at airports to increase security, saying any invasion of privacy was worth the enhanced ability to prevent terror attacks.
People on the flight described a chaotic scene that began with a popping sound as the flight made its final approach to Detroit, followed by flames erupting at Abdulmutallab's seat. Jasper Schuringa, a Dutch passenger on the flight from Amsterdam, leaped across the aisle to grab the suspect, who according to authorities suffered burns on his legs.
Schuringa told CNN he saw that Abdulmutallab was holding a burning object between his legs.
"I pulled the object from him and tried to extinguish the fire with my hands and threw it away," Schuringa said. He said he heard fire extinguishers as he pulled Abdulmutallab out of his seat and dragged him to the front of the plane.
Abdulmutallab was moved Sunday from a hospital where he was treated for his burns to an undisclosed location in the custody of the U.S. Marshal's Service, according to Gina Balaya, a spokesperson for the federal prosecutor's office in Detroit.
In Nigeria, Abdulmutallab checked no baggage on his trip that originated in Lagos on a KLM flight to Amsterdam, where he changed planes to the Northwest flight, according to Harold Demuren, director-general of Nigeria's Civil Aviation Authority.
The suspect had a shoulder bag and went through the normal check-in process, with his passport and U.S. visa scanned, Demuren said Sunday. The multiple-entry U.S. visa was issued in London, England, in June 2008 with an expiration date of June 2010, Demuren said.
Abdulmutallab then passed through a walk-through metal detector and put his shoulder bag through an x-ray screening machine, Demuren said. He also said the suspect underwent "secondary screening" at the boarding gate for the KLM flight, according to officials of the Dutch airline.
The father of the suspect recently contacted the U.S. Embassy in Nigeria with concerns his son was planning something, a senior U.S. administration official said Saturday.
The father -- identified by a family source as Umaru Abdulmutallab -- contacted the U.S. Embassy "a few weeks ago" saying his son, Umar Farouk Abdulmutallab, had "become radicalized," the senior administration official, who is familiar with the case, told CNN.
A senior administration official told CNN on Sunday that the father's alert meant the suspect's U.S. visa would have come under greater scrutiny if he sought to renew it next June.
"After his father contacted the embassy recently, we coded his visa file so that, had he attempted to renew his visa months from now, it would have triggered an in-depth review of his application," the official said.
In addition, the embassy -- which has law enforcement, security and intelligence representatives on staff -- reported the father's concern to other agencies, the official said.
The father's information also was forwarded to the National Counter-Terrorism Center, and Abdulmutallab was added to a general watch list, a senior administration official said. But the official said "the info on him was not deemed specific enough to pull his visa or put him on a no-fly list."
A family source told CNN that Umaru Abdulmutallab -- who recently retired as chairman of First Bank PLC, one of Nigeria's premier banks -- had contacted the embassy in Nigeria's capital, Abuja, and various other security agencies earlier than the timeline provided by the administration official. The family source said Abdulmutallab went to those agencies about three months ago after receiving a text message from his son.
The source, who lives at the family home in Kaduna in northern Nigeria, said the son informed his family in the text message that he was leaving school in Dubai to move to Yemen. He implied that he was leaving "for the course of Islam."
The family member said Abdulmutallab "had no family consent or support," adding he "absconded to Yemen."
Abdulmutallab went to Dubai to study for his masters degree in international business around January, 2009; he left Dubai about three months ago to go to Yemen, the family source said.
On Sunday, Nigerian Information Minister Dora Akunyili said Abdulmutallab returned to Nigeria on Dec. 24 and immediately left again on the flight to Amsterdam.
"The man in question has been living outside the country for a while," Akunyili said. "He sneaked into Nigeria on Dec. 24, 2009 and left the same day."
Abdulmutallab made an initial court appearance Saturday afternoon at the University of Michigan Medical Center in Ann Arbor, where he was being treated for burns suffered when he allegedly ignited a small explosive device.
A preliminary FBI analysis found that the device contained PETN, also known as Pentaerythritol Tetranitrate, a highly explosive chemical compound also present in the failed terror attack on an airliner by "shoe bomber" Richard Reid. In addition, FBI agents recovered what appear to be the remnants of a syringe from the vicinity of Abdulmutallab's seat, believed to have been part of the device.
A federal security bulletin obtained by CNN said Abdulmutallab claimed the explosive device used Friday "was acquired in Yemen along with instructions as to when it should be used."
Yemeni authorities have yet to receive official information on the terror attempt, according to a Yemeni official who asked not to be named because he is not authorized to speak to the press. But, the source said the country's government will take immediate action once the attempted bombing suspect's alleged link to the country is officially identified.
Also Saturday, the Netherlands' national coordinator for counterterrorism told CNN that Abdulmutallab had gone through "normal security procedures" in Amsterdam before boarding the flight to Detroit, and those were "well-performed."
U.S. Rep. Bennie Thompson, D-Mississippi, who chairs the House Committee on Homeland Security, said the attempted act of terrorism would be the focus of an oversight hearing next month. Sen. Jay Rockefeller, D-West Virginia, also said his Senate Commerce, Science and Transportation Committee would hold a hearing on the incident.