Shahzad has been cooperating with investigators and the arraignment's delay suggests he continues to give investigators valuable information, the Times reports. The docket in Shahzad's case doesn't list a defense lawyer and it's unclear if he's been assigned counsel.
Since Shahzad's arrest late Monday night, when he was taken into custody aboard a Dubai-bound flight, investigators have been probing possible links to Pakistani militant groups.
Shahzad, who said he acted alone, claimed to have received explosives training in the lawless tribal region of Waziristan. That stoked fears that the failed bombing was part of an international plot.
But U.S. officials say they have so far been unable to verify Shahzad's claims and have not yet linked him to any terrorist group.
Investigators say the crude, ineffective car bomb did not demonstrate the kind of explosives training terror groups normally provide ahead of a bombing operation.
The officials spoke on condition of anonymity because they were not authorized to discuss the investigation.
New York Police Commissioner Raymond Kelly said Wednesday that Shahzad apparently put his plan in motion in March, a month after he returned from Pakistan.
Any international organization that could take responsibility for the attack might try to claim it as a victory, even though the bomb failed to detonate. That's because, like the failed Christmas Day airline bombing, it would demonstrate a group's ability to carry out operations in the United States.
The Pakistani Taliban originally took responsibility for the Times Square bomb attempt, but officials have said there was no evidence that was true. Azam Tariq, a spokesman for the group, told CNN on Wednesday that his group did not train Shahzad.
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