One of the nation's most wanted terrorists is being linked to last year's thwarted plot to bomb the city's subway system.
Counterterrorism officials believe Adnan el Shukrijumah met with one of the would-be suicide bombers.
Officials say Shukrijumah, 34, is among the top candidates to be al-Qaida's next head of external operations, to be in charge of planning worldwide attacks.
He has eluded the FBI for years, and there is a $5 million reward for information leading to his arrest.
Najibullah Zazi pleaded guilty to plotting to attack New York targets with homemade bombs.
Authorities have said three people traveled from the city to Denver last summer and used stolen credit cards to help Zazi buy ingredients normally used in homemade bombs.
U.S. Attorney General Eric Holder called it one of the most dangerous plots since the September 11th terrorist attacks.
Zarein Ahmedzay also pleaded guilty in the plot and Adis Medunjanin is still awaiting trial.