An Afghanistan-born Colorado man who allegedly received al Qaeda training and had bomb-making instructions on his computer faced a court appearance Monday as the government warned law enforcement around the nation about the danger of an attack on mass transit.
Investigators say Najibullah Zazi, a 24-year-old airport shuttle driver, played a direct role in an alleged terror plot that unraveled during a trip to New York City around the anniversary of the Sept. 11 anniversary. But he has only been charged with lying to the government, and has a court appearance Monday afternoon in Denver on the charge.
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.
Publicly, law enforcement officials have repeatedly said they are unaware of a specific time or target for any possible attacks. Privately, officials speaking on condition of anonymity because they weren't authorized to discuss the case said investigators have worried most about the possible use of backpack bombs on New York City mass transit trains, similar to attacks carried out in London and Madrid.
Backpacks and cell phones were taken from apartments in the Queens raids last week.
A joint FBI-New York Police Department task force feared Zazi may have been involved in a potential plot involving hydrogen peroxide-based explosives like those cited in an intelligence warning issued last week, according to two law enforcement officials, who spoke on condition of anonymity because they were not authorized to speak about the investigation.
Authorities told CBS News that they couldn't rule out the alleged terror plot against New York Cityby other potential conspirators.
On Monday, federal officials reminded law enforcement across the country that rail and transit systems can be vulnerable to terrorist attacks.
In a joint assessment, the FBI and Homeland Security Department warned that improvised explosive devices are the most common tactic to blow up mass transit and rail systems overseas. And they noted incidents where homemade bombs made with various types of peroxide.
In the assessment, obtained by The Associated Press, officials recommended that transit system security officials conduct random sweeps at terminals and stations and that law enforcement make random patrols and board some trains and buses.
Zazi and his 53-year-old father, Mohammed Wali Zazi,Saturday in Denver. Ahmad Wais Afzali, 37, was arrested in New York, where he is an imam at a mosque in Queens.
The three are accused of making false statements to the government. The Zazis were scheduled to appear in federal court in Denver on Monday. Afzali was to appear Monday in federal court in New York.
If convicted, they face eight years in prison.
The younger Zazi has publicly denied being involved in a terror plot. His attorney, Arthur Folsom, dismissed as "rumor" any notion that his client played a crucial role.
Mohammed Zazi and Afzali are accused of lying to FBI agents about calls between Denver and New York. An affidavit accuses Afzali of lying about a call in which he told Najibullah Zazi that he had spoken with authorities.
Zazi's father is accused of lying when he told authorities he didn't know anyone by the name of Afzali. The FBI said it recorded a conversation between Mohammed Zazi and Afzali.
Prosecutors have said they're not seeking to detain Zazi's father. It was unclear whether they would seek to detain Afzali, who has worked as an informant for New York police.
"The parts don't fit together," said CBS News legal analyst Andrew Cohen. "The whole story clearly hasn't been told. If the facts in the supporting documents are true and could be proven, you would think the Zazis and their New York counterpart would already have been charged with providing material support to a terror group - and yet that hasn't happened.
"One theory is that the feds hoped (or still hope) that these three men will help them get information about other potential suspects. The problem with that theory is that if these men didn't do anything more than lie to authorities, there may not much of a larger story for them to tell."
Federal authorities, however, tell CBS News justice and homeland security correspondent Bob Orr they are convinced the young man is the "real deal" - a homegrown terrorist with real links to Islamic militant groups overseas.
Law enforcement sources tell Orr this is the most significant U.S.-based terror investigation since 2001 - and that there may well be more arrests before the investigation is concluded. The sources tell Orr it is quite possible Zazi is linked to a larger terror cell inside the United States.
Orr reports that the key information still missing is what, exactly, Zazi was hoping to do. Officials say he was plotting some kind of bombing campaign, but it hasn't yet become clear what he planned to target, or whether it was intended to be a large device or smaller "backpack bombs".
Carl Tobias, a University of Richmond law professor who tracks such investigations, said authorities could have made the arrests because they feared too much information was getting to the suspects. Additional charges could be filed later, he said.
CBS News correspondent Don Teague reports that Najibullah Zazi first appeared on the FBI's radar screen in August of 2008, when, according to court documents, he traveled to a region in Pakistan known as "ground zero" in the war against Islamic militants.
Authorities began monitoring Zazi when he returned in January this year, including wire-tapping his phones. They became increasingly suspicious early in September when Zazi rented a car and drove 30 hours to New York City.
Ron Kuby, Afzali's attorney, said his client gave authorities a DNA sample and let them search his home after the FBI said it was "frantic for any information about Zazi." Kuby said Zazi's trip to New York may have forced authorities to make the arrests.
CBS News chief investigative correspondent Armen Keteyian reports that Afzali is now charged with lying to authorities about court-authorized wiretapped conversations on Sept. 10 and 11 - including one in which Afzali allegedly tipped off Zazi and his father (seen at left) about the FBI's interest in them and several other men.
Kuby called the charges groundless and said Monday that his client had fully cooperated with the FBI, and was aware all along that his phone calls were being monitored.
"Why in the world is he going to lie about the content of a conversation that he knew was being taped?" Kuby said outside the Brooklyn courthouse where Afzali was to appear later in the day.
He accused authorities of trying to make Afzali a scapegoat for a botched investigation.
"The government wants somebody to blame for the fact that they haven't caught any terrorists," he said.
An arrest warrant affidavit alleges Zazi admitted to FBI agents that he received instruction from al Qaeda operatives on subjects such as weapons and explosives. It also says he received the training in the federally administered tribal areas of Pakistan.
"I think this demonstrates, despite what some have said, that the safe haven in Pakistan and al Qaeda core still matter; they still matter because there is training underway," said CBS News national security analyst Juan Zarate. "There are Westerners, including people from the U.S., who are willing to travel there to connect to al Qaeda to be launched and sent back."
The FBI said it found images of handwritten notes on a laptop containing formulas and instructions for making a bomb, detonators and a fuse. Zazi told the FBI that he must have unintentionally downloaded the notes as part of a religious book and that he deleted the book "after realizing that its contents discussed jihad."
An affidavit says the handwriting on the notes appeared to be Zazi's. It also says they were e-mailed in December as an attachment between accounts believed to be owned by Zazi, including an account that originated in Pakistan.
FBI agents say Najibullah Zazi traveled to Pakistan twice this year. Zazi says he was visiting his wife, who lives in the Peshawar region.
Zazi was born in Afghanistan, moved to Pakistan at age 7 and emigrated to the United States in 1999. He returned to Pakistan in 2007 and 2008 to visit his wife, according to Folsom.
Aaron Donovan, spokesman for the Metropolitan Transportation Authority, said the MTA was in touch with the New York City area's joint terrorism task force, but wouldn't comment Monday on any communications it had received from the NYPD or FBI. The agency operates the city's subways - carrying about 8 million daily riders - and commuter rail lines.