The suspect in a Times Square bombing attempt attended a terrorist training camp in Pakistan, U.S. law enforcement officials said Tuesday.
Faisal Shahzad was arrested late Monday for trying to blow up an SUV two days earlier.
Authorities brought terrorism and mass destruction charges against Shahzad on Tuesday and said in court documents he had confessed to receiving explosives training in Waziristan, Pakistan, a lawless tribal region where the Pakistani Taliban operates with near impunity. The group has claimed responsibility for the attack, but officials say there's no evidence to back that up.
Much of the investigation into the attempted bombing has now moved to Pakistan.
"We have to see whether it was an individual act or if it was a collective kind of act," a Pakistani official said.
Shahzad told the authorities that he had acted alone, but hours after he was arrested, security officials in Pakistan said they arrested at least five people in connection with the bombing attempt, NBC reported.
Some media reports described them as relatives of Shahzad.
Officials on Tuesday said no charges had been filed.
Shahzad was on board a Dubai-bound flight that was about to taxi away from the gate at New York's Kennedy Airport late Monday when the plane was stopped and FBI agents and New York Police Department detectives took him into custody, law enforcement officials said.
U.S. officials have said the 30-year-old had recently returned from a five-month stay in Pakistan, raising speculation he may have been in contact with al-Qaida or Taliban groups in the South Asian country.
The officials spoke on condition of anonymity to discuss the investigation.
Pakistani connection
Pakistani officials identified one of the detainees as Tauhid Ahmed and said he had been in touch with Shahzad through e-mail, and had met him in the United States or in the Pakistani port city of Karachi.
Another man arrested, Muhammad Rehan, had spent time with Shahzad during a recent visit there, Pakistani officials said. Rehan was arrested in Karachi just after morning prayers at a mosque known for its links with the militant group Jaish-e-Muhammad.
Others, who Pakistani police have rounded up are also believed to be facilitators of Shazad. They are: a man named Iftikhar from Karachi, a woman who has not yet been named, Muntaz Billa a.k.a Imtiaz Askari from Sumandri near Faisalbad, and one other man who has not yet been named.
Rehman Malik, Pakistan's interior minister, said Shahzad is from a small village outside of Peshawar, called Pabbi.
His family is believed to have moved to Haytabad, a posh suburb of Peshawar. His family also has a home in Islamabad. His father is believed to be a retired Air Force officer.
Both Shazad and his wife, Huma Mian, were schooled at universities in the United States.
Several Pakistani officials said U.S. authorities had not made a formal request for the country to help in the probe.