Last week's terrorist threat to New York's subways might have been a hoax, but authorities have not found the informant to question him further, sources told NBC on Tuesday.
An informant in Iraq told U.S. military officials last week that a terrorist attack was planned against New York City's subway system, prompting the city to sharply increase security on trains over the weekend.
On Tuesday, the New York Post reported that sources said the claim was a hoax.
But three federal officials told NBC News' Pete Williams on Tuesday that it was premature to conclude the source made up his story.
The sources, who spoke on condition of anonymity because they weren't authorized to discuss the case, said that after initially questioning the informant and giving him a polygraph test, his U.S. military handlers released him. He was never under arrest, the sources said.
Since then, the sources said, no one has found the man to ask him specifically if he made up the claim that al-Qaida operatives in Iraq were scheming to attack the subways using baby strollers and briefcases packed with remote-controlled explosives.
Two of the sources, however, said there was reason to believe that he made up the story, possibly for money. One source said this conclusion was based on talks with others who know the informant.
Federal and city officials debated the credibility of the terror claim almost from the start.
A Department of Homeland Security memo said that the agency and the FBI doubted the threat's credibility.
Despite this, city officials sharply increased security in the subways. As they scaled back on Monday, they stood by their decision, saying the initial tip had come from an informant with a reputation for reliability and was too specific to ignore.
“We did precisely the right thing,” New York City Police Commissioner Raymond Kelly said. “We had no choice but to respond the way we did.”