Monday a 24-year-old Afghan man Zazi at the center of an unfolding FBI investigation into a possible U.S. terrorism cell was ordered held without bond in Colorado Monday. Authorities raced to learn more about an alleged plot using hydrogen peroxide explosives and who else might have got involved.
Meanwhile, authorities in Washington and elsewhere were stepping up safety patrols on mass transit systems in response to an advisory issued in connection with the probe.
Officials with the Department of Homeland Security and the FBI sent a bulletin to transit agencies Friday repeating past warnings to be on guard for attacks on mass transit systems, and identifying hydrogen peroxide-based explosives as a specific risk. Federal officials called the notice "precautionary", and said it included possible countermeasures such as random checks of stations, trains and buses, The Washington Post reports.
It was also reported, federal authorities have tied as many as a dozen people to a suspected Al Qaeda-linked bomb plot on U.S. soil as they continue to gather evidence to indict on terrorism charges the young Afghan immigrant at the center of the case.
Authorities said that they did not know the exact number of potential suspects or many of their identities, but that they had been connected through electronic intercepts, surveillance, seized evidence and interviews.
A federal law enforcement official and others, speaking on condition of anonymity because of the high level of secrecy surrounding the investigation, said the suspects appeared concentrated in the New York area, with possibly others in the suspect's home state of Colorado and elsewhere, The Los Angeles Times reports.
In the bulletin, obtained by The Associated Press, officials recommended that transit systems conduct random sweeps at terminals and stations and that law enforcement make random patrols and board some trains and buses.
The effects of the warning were not immediately clear Monday. New York's transit agency said it was in touch with an FBI-NYPD task force but wouldn't comment further.
The task force feared Zazi may have been involved in a potential plot involving hydrogen peroxide-based explosives, according to two law enforcement officials, who spoke on condition of anonymity because they were not authorized to discuss the investigation.
Investigators said they found notes on bomb-making instructions that appear to match Zazi's handwriting, and discovered his fingerprints on materials — batteries and a scale — that could be used to make explosives. He also made a trip to Pakistan last year in which he received al-Qaida explosives and weapons training, the government said, The Associated Press reports.