Shahzad, the man accused of trying to detonate a car bomb in Times Square, spent a decade on the path to respectability before abandoning his house in Connecticut and deciding to supplement his business degrees with explosives training in Pakistan, authorities say.
Law enforcement sources tell CBS News motives pursued include religion (did he attend a mosque frequently?), hatred of Americans and money. The source said investigators are trying to figure it out as they continue to track his movements including where he was following the incident and who may have helped him and think there are those they helped Shahzad unwittingly.
The 30-year-old son of a retired official in Pakistan's air force was charged Tuesday with trying to blow up a crude gasoline and propane device inside a parked SUV amid tourists and Broadway theatergoers. He was in custody after being hauled off a Dubai-bound plane he boarded Monday night at John F. Kennedy International Airport despite being under surveillance and placed on the federal no-fly list.
Passengers disembarking from the flight many hours later described a calm scene as he was removed from the plane. They said he didn't put up a struggle.
U.S. Attorney General Eric Holder said Shahzad had been providing valuable information to investigators as they sought to determine the scope of the plot to blow up the SUV last Saturday night in the heart of Times Square near bustling restaurants and a theater showing "The Lion King."
"Based on what we know so far, it is clear that this was a terrorist plot aimed at murdering Americans in one of the busiest places in our country," Holder said.
A court hearing was canceled Tuesday in part because of Shahzad's continuing cooperation with investigators, but authorities said they had shed little light on what might have motivated him.
Sources tell CBS News there is no evidence Shahzad was part of a broader plot. But investigators are very interested in Shahzad's recent stay in Pakistan - he was there for several months - and the FBI wants to find out who else he had contact with, reports CBS News Justice correspondent Bob Orr.
Until recently, his life in the U.S. appeared enviable. He had a master's degree from the University of Bridgeport in Connecticut, a job as a budget analyst for a marketing firm in Norwalk, Conn., two children and a well-educated wife who posted his smiling picture and lovingly called him "my everything" on a social networking website.
But shortly after becoming a U.S. citizen a year ago, he gave up his job, stopped paying his mortgage and told a real estate agent to let the bank take the house because he was returning to Pakistan.
Once there, according to investigators, he traveled to the lawless Waziristan region and learned bomb making at a terrorist training camp.
CBS Evening News: Inside the life of Faisal Shahzad
In court papers, investigators said Shahzad returned to the U.S. on Feb. 3, moved into an apartment in a low-rent section of Bridgeport, then set about acquiring materials and an SUV he bought with cash in late April. They said that after his arrest, Shahzad confessed to rigging the bomb and driving it into Times Square. He also acknowledged getting training in Pakistan, the filing said.
The investigation of the fizzled bomb attack unfolded quickly, with a suspect in custody in only 53 hours - but it didn't go off without a hitch.
After identifying Shahzad through the previous owner of the SUV, investigators had him under surveillance when he nearly slipped away.
Authorities initially planned to arrest him at his Connecticut home but lost track of him, two people familiar with the probe told The Associated Press. The people spoke on condition of anonymity because they weren't authorized to talk publicly about the breach in surveillance.
Emirates airlines also didn't initially notice when Shahzad purchased a ticket that he had been placed on the government's no-fly list, according to a law enforcement official.
U.S. Department of Homeland Security Secretary Janet Napolitano credited customs officials with recognizing Shahzad's name on a passenger manifest and stopping the flight. Agents apprehended him on the plane.
Passengers said the arrest was made quietly. First-class passenger Samir al-Ammari, a Saudi who was in the U.S. on a business trip, said he saw security surround the suspect.
"Honestly, I was worried," he said. "I was planning to cancel the flight and get another one."
Several passengers said the revelation there was a link to the failed Times Square bombing didn't cause a panic.
"There was no commotion, no general alarm or concern," said Robert Woodward, of Boulder, Colo.
A gun was discovered in the car Shahzad left at the airport, investigators said.
Kifyat Ali, a cousin of Shahzad's father, spoke with reporters outside a two-story home the family owns in an upscale part of Peshawar, Pakistan. He said the family had yet to be officially informed of Shahzad's arrest, which he called "a conspiracy so the (Americans) can bomb more Pashtuns," a reference to a major ethnic group in Peshawar and the nearby tribal areas of Pakistan and southwest Afghanistan.
The Pakistani Taliban has claimed responsibility for the Times Square car bomb plot, but U.S. officials said they are still investigating. Federal authorities are looking into possible financing of Shahzad's activities by the group, according to one of the law enforcement officials who spoke to the AP. A spokesman for Pakistan's army said Wednesday that it does not believe the insurgent group was behind the attempt.
In Pakistan, authorities detained several people, although the FBI said it had no confirmation that those arrests were relevant to the case.
Shahzad came to the U.S. in late 1998 on a student visa. Not long after earning his MBA, he took a job at the Affinion Group, which does brand-loyalty marketing, and stayed there until leaving voluntarily in May 2009, a company spokesman said.
His path to citizenship was eased by his marriage to an American, Huma Mian. Like her husband, Mian was well-educated, with a business degree from the University of Colorado at Boulder.
On her profile on the social networking site Orkut, she described herself as "not political," said she spoke English, Pashto, Urdu and French and listed her passions as "fashion, shoes, bags, shopping!! And of course, Faisal."
She posted a picture of Shahzad, smiling, with the caption, "what can I say ... he's my everything."