Federal authorities are closing in on the man they say is a person of interest in the Times Square car bomb attempt this weekend, who is described as a naturalized American citizen who hails from Pakistan and just returned after spending five months there.
There is growing evidence the bomber did not act alone and had ties to radical elements overseas, with one senior official telling ABC News there are several individuals believed to be connected with the bombing and that at least one of them is a Pakistani-American.
Attorney General Eric Holder said today the investigators had made "substantial progress" in tracking the man who drove a Nissan Pathfinder into New York's Times Square with a crude bomb that failed to detonate.
Officials declined to provide the specifics that led them to believe there were overseas links to a larger plot.
Authorities said another clue in the investigation is a video posted online early Sunday morning by persons in Connecticut, who may have been involved in the bomb attempt and are being sought by law enforcement. The video, posted on a site registered one day before the attack, has the Taliban in Pakistan claiming responsibility for the attempted bombing.
The Washington Post, quoting Obama Administration sources, said the attempted bombing "increasingly appears to have been coordinated by several people in a plot with international links."
Other law enforcement officials said the investigation was closing in on the driver of the vehicle and an unknown number of others connected to him.
"This is moving very fast because they left behind a treasure trove of evidence in the unexploded car," one US official told ABC News.
Officials told ABC News Senior Justice correspondent Pierre Thomas that the Connecticut owner of the vehicle told them he had sold the Nissan SUV last month in an unrecorded sale to an "Arabic or Latino looking man" in his 20's or 30's, for a few hundred dollars in cash.
The license plate on the car was apparently stolen from an auto repair shop outside Bridgeport, Connecticut, according to law enforcement officials.
The authorities told ABC News that the previous owner provided a description of the man who bought the car, and told investigators the vehicle was sold for several hundred dollars in cash, with no written records identifying the purchaser.
The license plate found on the Pathfinder also came from Connecticut, #98CY09, according to photographs of the vehicle.
Times Square Bomb
Authorities tell ABC News that the plate came from a vehicle that was in a repair shop near Bridgeport, Connecticut.
Meantime, police are now engaged in an urgent manhunt for a man caught on tape near the SUV, loaded with propane, fireworks, fertilizer and timing devices.
Though a Taliban leader thought killed in a U.S. drone strike has now resurfaced in a video threatening attacks on U.S. cities, and the Taliban has claimed credit for the failed New York attack, U.S. authorities are skeptical.
According to police, surveillance shots from a half block away from the site of the Saturday incident may give clues to the person responsible.
The New York City Police Department has released video showing a white male in his 40s looking back in the direction of West 45th street. He can also be seen in the video shedding a dark-colored shirt, revealing a red one underneath.
On Good Morning America, New York City Mayor Mike Bloomberg was cautious in his description of the man on the surveillance tape, calling him "a person of interest."
Bloomberg expressed confidence that whoever was responsible for the failed attack would be caught. "There's a high probability we will find out who did this," said Bloomberg. "There's a lot of evidence."
The would-be bomber packed the car with more than 100 pounds of fertilizer, but not the kind that would explode, police said.
Had the bomber chosen the right kind of fertilizer, the bomb would have had the force of more than 100 pounds of TNT. But instead of ammonium nitrate, the kind of fertilizer used by Oklahoma City bomber Timothy McVeigh, the bomber used a harmless fertilizer, New York City Police Department spokesman Paul Browne said.
A surveillance camera captured an image of the car crossing Broadway through pre-theater crowds just before 6:30 p.m. Saturday. The car was left on W. 45th Street with its lights flashing and engine running.
The surrounding area was evacuated after street vendor Duane Jackson saw smoke coming from the Pathfinder and alerted police. Jackson, who has been working in Times Square for 13 years, said he is always on alert in the crowded public space, and in touch with police. "Vigilance is the key," said Jackson. "Keep your wits about you [and] don't take anything for granted."
Police moved back thousands of theatergoers and tourists as the bomb squad moved in.
Technicians blew open the back doors and trunk and found the car packed with propane canisters and gasoline containers.
"Clearly it was the intent of whoever did this to cause mayhem," said New York police commissioner Ray Kelly.
But the detonator, alarm clocks hooked up to fire crackers, failed to work.
"They would not have been able to have stopped the bomb if it had been wired properly," said former counterterrorism czar Richard Clarke, now an ABC News consultant. "Someone was able to drive into New York with what looks like bomb parts, drive right into the heart of Times Square, pull up on the sidewalk, jump up and run away and not get caught."
The bomb bore similarities to two Al Qaeda-connected attacks on a London nightclub and an airport in Scotland in 2007. Three vehicles used in the attempted bombings contained propane gas tanks.
Al Qaeda has posted videos showing how to construct a bomb using propane tanks and gasoline.
On Sunday night, the Taliban released a video featuring Hakimullah Mehsud, who U.S. and Pakistani authorities had thought was killed in a drone strike in January.
On the recording Mehsud can be heard saying, "The time is very near when our fedayeen will attack the American states in their major cities." He also claims that Taliban fedayeen "have penetrated the terrorist America, we will give extremely painful blows to the fanatic America."
Mehsud's video was recorded April 4, and Mehsud threatens attacks in the days and weeks to come.
Earlier, in the hours after the failed Times Square bombing, a Taliban group in Pakistan claimed responsibility for what it called a "jaw-breaking blow to Satan's USA.
But U.S. officials expressed doubt about a Taliban connection.
Mayor Bloomberg said that so far there was "no legitimate evidence" the Taliban or al Qaeda were involved. "There's one group of the Taliban that claims credit for everything, including traffic jams," said Bloomberg.
Homeland Security Secretary Janet Napolitano noted on Good Mormng America that there is a history of groups trying to claim credit for attacks. But she did not rule out any groups. "What we have is a real attempt at an attack," said Napolitano. "Law enforcement is pursuing leads."