JACKI LYDEN, host:
Here's what prosecutors have told us so far about the main suspect in an alleged plot to bomb transportation targets in New York City.
His name is Najibullah Zasi. He allegedly went to an al-Qaida training camp in Pakistan last year. He allegedly bought gallons of chemicals to make a bomb. And he allegedly cooked up the explosives in a hotel room.
The case against him is based on these charges and more. But how did law enforcement first learn these things?
NPR's Dina Temple-Raston reports on how the government conducts a terrorism investigation.
DINA TEMPLE-RASTON: Prosecutors have already informed Zazi's lawyer and the judge in the case that much of the evidence they'll present at trial came from a wiretap.
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TEMPLE-RASTON: Now, if you've ever watched "The Wire" on television, you know a little something about Title Three wiretaps.
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Unidentified Man:(Singing) When you walk through the garden, you better watch your back...
TEMPLE-RASTON: Title Three wiretaps are named for a section in the Criminal Code, and mostly they're used to catch mobsters or drug dealers. To get this kind of wiretap, police have to convince a judge that the wire is likely to pick up evidence of a crime.
The wiretap used on Zazi was different. In this case, officials got what they called a Roving FISA Wiretap. FISA stands for Foreign Intelligence Surveillance Act. Former FBI Assistant Director Tom Fuentes says these wiretaps used to be all about espionage. That's all changed.
Mr. TOM FUENTES (Former Assistant Director, FBI): In certain cases, obviously, an act of terrorism against the United States affects national security, and so under certain circumstances terrorism also qualifies.
TEMPLE-RASTON: Law enforcement officials close to the Zazi case tell NPR that the FBI applied to a special court for the wiretap months ago. Sources say officials acted after Pakistani intelligence allegedly told them that Zazi had met with al-Qaida operatives there. Zazi returned to the U.S. in January and the FBI was tracking him, not on a daily basis but in a way that they could keep tabs on him.
Sources say the wiretaps were vital to the investigation. For example, officials tell NPR the wiretap picked up a Zazi phone conversation about chemical mixtures for explosives. In another intercept, officials allege he was frantically calling and texting several people about bomb-making. That information led officials to use another tool: they stepped up surveillance on Zazi.
Sam Rascoff used to work in the Intelligence Unit at the New York Police Department.
Mr. SAM RASCOFF (Former Intelligence Analyst, NYPD): I think what's striking about the Zazi case is not so much that new tools were being used, but that old tools were being used in a comprehensive fashion and that they were being stitched together in a thoughtful, strategic way, so that one tool naturally gave way to another.
TEMPLE-RASTON: Here's another example. At the end of the summer, physical surveillance on Zazi ramped up. He surprised the agents by renting a car and starting to drive cross-country. FBI agents followed him and just to make sure they tracked Zazi closely, they asked local law enforcement for help along the way. Zazi was pulled over several times for speeding. He apparently got a ticket in Kentucky and the FBI knew all about it.
When Zazi neared New York City on September 10th, the New York police pulled him over on the George Washington Bridge. Officials wanted to make sure there weren't any chemicals or a bomb in Zazi's car, so they told Zazi it was just a routine search and they pulled over other cars too.
Mr. ART FOLSOM (Zazi's Attorney): The stop was, at least allegedly, for a random drug checkpoint.
TEMPLE-RASTON: That's Zazi's lawyer, Art Folsom.
Mr. FOLSOM: They searched his vehicle. They found nothing and sent him on his way.
TEMPLE-RASTON: And what did he think about that?
Mr. FOLSOM: He thought this was just one of those law enforcement things that happens every now and then. He didn't think anything of it at that point.
TEMPLE-RASTON: Authorities got a better look at Zazi's car a day later. They used a special provision of the Patriot Act known as a Sneak and Peek. They broke into the car and they swabbed it for chemicals. They found Zazi's laptop in the car and they copied the hard drive. And then they very carefully put everything back just where they found it. Zazi had no idea that they'd been there. Officials say they found bomb-making instructions on that computer.
Now, evidence in the case is still very closely held. Officials are still tracking a handful of other men they believe were helping Zazi in this plot.
Sam Rascoff, the former NYPD official, said that even with the limited evidence revealed so far, the Zazi investigation shows how many tools can be brought to bear in a domestic terrorism case.
Mr. RASCOFF: They can use electronic surveillance, which is just a fancy term for eavesdropping on phone calls and looking into e-mails; undercover agents and confidential informants who are on the inside of organizations; and they can use physical surveillance, what you and I would call casing a joint or following a person.
TEMPLE-RASTON: And in the Zazi case, it seems like they used them all.
Mr. RASCOFF: They sure did.
TEMPLE-RASTON: But they aren't done yet. Officials haven't explained where the bomb materials ended up. And they tell NPR more arrests are coming.
Dina Temple-Raston, NPR News, New York.