New York (CNN) -- Charges filed Tuesday against Times Square car bombing suspect Faisal Shahzad paint him as a would-be terrorist who sought explosives training in Pakistan's volatile Waziristan region, where government forces have been working to root out Taliban militants.

The court documents show Shahzad apparently continued to have contact with Pakistan upon his return to the United States, receiving a series of 12 phone calls originating from his country of birth in the days leading up to the incident -- five of which were made on the same day he bought the Nissan Pathfinder used in the attempted attack Saturday night.

Those phone calls ceased just three days before the failed bombing, the documents show.

"It is clear that this was a terrorist plot," Attorney General Eric Holder said Tuesday. It could have caused "death and destruction in the heart of New York City."

Five federal charges were filed against Shahzad on Tuesday in U.S. District Court: attempting to use a weapon of mass destruction, acts of terrorism transcending national boundaries, use of a destructive device in connection with criminal violence, transporting and receiving explosives, and damaging and destroying property by means of fire.

If convicted, Shahzad faces up to life in prison on the charges.

Shahzad has waived his right to remain silent and his right to an attorney, and is cooperating in the investigation, a source familiar with the probe said.

Shahzad, 30, a naturalized U.S. citizen from Pakistan who was living in Connecticut, was arrested at New York's John F. Kennedy airport late Monday after boarding a flight bound for Dubai, United Arab Emirates.

He was due in federal court later Tuesday, but that appearance was delayed until at least Thursday as he continued to be questioned by authorities.

"This incident is another sobering reminder of the times in which we live," President Obama said Tuesday. "Around the world and here at home, there are those who would attack our citizens and who would slaughter innocent men, women and children in pursuit of their murderous agenda. They will stop at nothing to kill and disrupt our way of life."

The court documents allege that Shahzad admitted to investigators to driving the Pathfinder into Times Square and attempting to detonate the bomb. The documents also reveal a clearer picture of how he was linked to the plot.

Read complaint filed in federal court Tuesday (PDF)

After receiving explosives training at a camp in Pakistan's Waziristan region, Shahzad returned to the United States via a one-way plane ticket February 3, the court documents say, citing Customs and Border Protection records.

He told immigration officials upon his return that he had been visiting his parents in Pakistan for five months, according to the documents. He also told officials that his wife remained in Pakistan.

Authorities focused on Shahzad when they traced evidence to him from the sale of the Nissan Pathfinder used in the failed attack, information considered the linchpin of the case.

The SUV's vehicle identification number had been removed from the dashboard. Police retrieved the VIN from the bottom of its engine block.

This, said a federal law enforcement official, led investigators to the registered owner of the vehicle and then to Shahzad, who purchased the SUV on April 24 for $1,300 cash via an ad on the internet, the court documents show. He was identified in a photo lineup by the seller of the vehicle.

Latest updates in Times Square bomb scare

In addition to the bomb-making materials found in the Pathfinder -- which included gasoline, propane tanks, fireworks and non-explosive fertilizer -- investigators found a set of keys, one of which opened Shahzad's Connecticut home. Another belonged to an Isuzu vehicle. Shahzad is believed to have driven an Isuzu to the airport Monday.

Phone records cited in the court documents show a series of calls made from Pakistan to a pre-paid cell phone used by Shahzad. The phone was activated April 16 and inactivated around April 28, last Wednesday. The attempted attack was carried out Saturday.

Watch reaction from Pakistan on Shahzad's arrest

Fireworks used in the attempted car bombing were purchased from a store in Pike County in northeastern Pennsylvania, a federal law enforcement source said Tuesday.

The source says the M-88 fireworks Shahzad is accused of placing in the Nissan Pathfinder were bought at a Phantom Fireworks store in Matamoras, Pennsylvania.

A complaint filed Tuesday in U.S. District Court says Shahzad made a phone call to an unnamed Pennsylvania fireworks store.

Bruce Zoldan, the president of Phantom Fireworks, which has 55 stores across the country, would not confirm exactly what was purchased, or when, so as not to compromise the investigation. But he did confirm that the Matamoras store sells M-88 Silver Solutes, which are similar to what was found in the Nissan Pathfinder.

Zoldan says his company has been in touch with the FBI from the beginning of the investigation. The company's national security director is a retired member of the FBI, Zoldan says, and is currently dealing with active members of the FBI and exchanging information.

The company's vice president, William Weimer, says the M-88s are legal to purchase by consumers because they have a limited amount of pyrotechnic composition and are not very strong.

"The products simply do not chain detonate as I'm sure the culprit anticipated they would," Weimer said.

FBI agents searching Shahzad's Connecticut residence recovered fireworks and fertilizer from his garage, the documents say.

Timeline in bomb plot

As the investigation drew law enforcement officials closer to finding Shahzad, he was placed on a federal no-fly list Monday, according to FBI Deputy Director John Pistole. The restriction helped Customs and Border Protection agents arrest him moments before Emirates Flight 202 to Dubai pushed back from the gate.

Two other passengers were removed from the plane "out of an abundance of caution" after it left the gate, a federal law enforcement source said. Those passengers were later cleared and released.

In addition, Emirates airline said Shahzad bought his ticket with cash at the airport counter, and the staff, considering that unusual, immediately informed airport security officials.

A 9 mm gun found in a vehicle believed to have been driven to the airport Monday night by Shahzad was bought at a gun shop near his former home in Shelton, Connecticut, federal law enforcement sources said Tuesday.

The sources said Shahzad bought the semi-automatic Sub 2000 rifle less than two months ago at Valley Firearms in Shelton.

The purchase was legal, according to the sources.

Authorities were conducting surveillance of Shahzad on Monday, but they lost him before he arrived at the airport, a senior counterterrorism official said Tuesday.

An FBI official responded that surveillance operations are designed with redundancies in place, and that agents had to avoid tipping off Shahzad that he was being followed.

Hours after authorities arrested Shahzad, security forces in Pakistan seized two or three people in a raid in connection with the failed bombing, a Pakistani intelligence source said.

The Pakistan raid took place at a Karachi house where Shahzad was believed to have stayed during his last visit to the country.

Shahzad has a Karachi identification card, a sign of Pakistani residency, and his family is from volatile northwestern Pakistan, where government forces have been fighting Taliban militants who have strongholds in the area, according to Pakistani Interior Minister Rehman Malik.

U.S. law enforcement officials are happy with the level of cooperation coming out of Faisal's country of birth, said a source familiar with the probe. Officials in Pakistan have been sharing intelligence with U.S. authorities and asking those same authorities to share any information Shahzad provides about terrorist training camps in Pakistan, the source said.

Pakistani Ambassador to the United States Husain Haqqani told CNN's "Situation Room" Tuesday night that, "It's an investigation in which Pakistan will stand by the side of the United States," adding that "Pakistanis want to defeat terrorism as much as Americans do."

Shahzad's father is a retired senior officer in the Pakistani Air Force, Shahzad's cousin, Kafayat Ali, said Tuesday.

The father, Bahar Ul Haq, a former air vice marshal, lives in the Peshawar suburb of Hayatabad in what is now Khyber Pakhtoonkhwa province, formerly the North West Frontier Province.

"This is certain, that these people, they never indulged in any criminal activities," Ali said. "Not a family member. Not the village from which both of these people belongs, none of the village members involved in any criminal activities or any jihad activities."

Shahzad also has a brother named Amir who lives in Canada, a police source said.

Shahzad became a U.S. citizen on April 17, 2009, which aided investigators in the case, the federal law enforcement source said. Because of his recent change in residency status, authorities had his picture and were able to show it to the seller of the vehicle.

A woman who said she lived next door to Shahzad in Shelton, Connecticut, until his family moved in July, said Tuesday that the man she knew was quiet and claimed to work on Wall Street in New York.

A spokesman for Affinion Media Group said Tuesday that Shahzad worked as a junior financial analyst for the marketing firm at the company's Norwalk, Connecticut, office from mid-2006 to June. The spokesman said Shahzad left the firm voluntarily.

CNN's Craig Bell, Deborah Feyerick, Samson Desta, Tim Lister, Jeanne Meserve, Susan Candiotti, Reza Sayah, Caroline Faraj, David Fitzpatrick, Drew Griffin, Carol Cratty and Frances Townsend contributed to this report.