“It’s a prominent lead that they’re following, the international association,” said a senior official, who spoke on condition of anonymity to discuss a continuing investigation. “But there’s still a lot of information being gathered.”

On Monday, prior to the arrest, there was a sweeping response to the attempted attack in the tourist-packed city-within-a-city of Times Square — including an increased police presence, vehicle inspections and a touch of panic from veteran New Yorkers when a manhole fire flared five blocks from the scene of the failed bombing. Consolidated Edison blamed faulty wiring for the fire.

The recent sale of the Pathfinder began online. An advertisement that appears to be for the vehicle, which had 141,000 miles on the odometer and was listed for sale at $1,300 on at least two Web sites, emphasized that it was in good condition — “CLEAN inside and out!!” — with a recently repaired alternator and a new gas pump, distributor and front tires. “It does have some rust as you can see in the picture,” the seller allowed on NothingButCars.net, “but other than that, it runs great.” The other advertisement appeared on Craigslist.

In Bridgeport, the seller refused to answer questions. “You can’t interview her,” said an unidentified man at the woman’s two-story, white clapboard house. “She already talked to the F.B.I.”

The police earlier on Monday continued sifting through footage from 82 city cameras mounted from 34th Street to 51st Street between Avenue of the Americas and Eighth Avenue, and from untold number of business and tourist cameras.

Image Plates on the Nissan Pathfinder were traced to a pickup truck being repaired at Kramer's Used Auto Parts in Stratford, Conn. Credit... Christopher Capozziello for The New York Times

But investigators appeared to have begun to assign less significance to a man who appeared to be in his 40s who was seen on one video, and it may well be because they were close to arresting the Connecticut man.