Zazi denies that he's a central figure in a terrorism investigation that fed fears of a possible bomb plot and led to several police raids in New York City on Monday.
Zazi, 24, was being interviewed at FBI headquarters in Denver late Wednesday but was not under arrest, according to his attorney, Arthur Folsom. Zazi provided authorities a DNA sample, a fingerprint, handwriting samples and information about his travel history, Folsom said.
"My client is not involved in any terror plot," Folsom declared. "He answered every question they had." The U.S. Attorney's Office in Denver said it had no immediate comment.
One agent wearing protective clothing escorted a dog belonging to the Bureau of Alcohol, Tobacco, Firearms and Explosives into Zazi's apartment. FBI agents left Zazi's apartment with at least six boxes. One box was labeled "swabs," and others were marked "fragile" and "glass."
Agents also escorted three women and a man from the apartment. Two of the women covered their faces with headscarves, and the third used a canvas chair to shield her face. All were driven away in an SUV.
The searches came a day after two law enforcement officials told The Associated Press that a joint FBI-New York Police Department task force had put Zazi under surveillance because of suspected links to al-Qaida.
The task force also feared Zazi may be involved in a potential plot involving homemade hydrogen peroxide-based explosives like those cited in an intelligence warning issued Monday, said the officials, who spoke on anonymity because they were not authorized to speak about the investigation.
After Zazi traveled to New York City over the weekend, FBI agents and police officers armed with search warrants seeking bomb materials searched three apartments and questioned residents in a predominantly Asian neighborhood in Queens.
Naiz Khan, an Afghan immigrant who grew up with Zazi in New York City, said the FBI questioned him for about two hours about Zazi, whom he said stayed at his apartment last week.
No arrests were announced, and the FBI and NYPD have refused to discuss the case.
New York Police Commissioner Raymond Kelly and FBI Director Robert Mueller said Wednesday there are no specific terrorist threats to the city.
"There are no guarantees. We live in a dangerous world," said Kelly, who called New York the world's best-protected city.
Monday's FBI and Homeland Security intelligence warning, issued to police departments nationwide, listed clues that could tip off police to peroxide-based bombs, such as people with burn marks on their hands, faces or arms; foul odors coming from a room or building; and large industrial fans or multiple window fans.
Colorado elected officials who said they've been briefed on the investigation have said there is no imminent threat.
Zazi's apartment building is very close to a toll road that runs to Denver International Airport, where he picks up and drops off passengers as a driver for ABC Airport Shuttle.
Denver city records show that when Zazi applied for a limousine driver license on Feb. 3, he said he had a permanent residence green card and had been in Denver one month. A limousine license was granted April 15, indicating Zazi passed a Colorado Bureau of Investigation background check and a driving record check.
On Tuesday, Folsom said Zazi contacted him immediately after hearing that friends' homes in New York had been raided.
The lawyer said Zazi drove to New York in a rented car to take care of a problem with the location of a coffee cart that he co-owns with a friend, and to visit friends.
Zazi said he was stopped by police on Sept. 10 on the George Washington Bridge, which connects New Jersey to Manhattan, and that he consented to a random search of his vehicle for drugs. He was allowed to leave.
In New York, Folsom said, Zazi's car was towed because of a parking violation. Police searched both the car and a laptop inside, Folsom said.
"They found nothing, didn't ask him any more questions and sent him on his way," Folsom said. "If they had found anything, he would be in the company of the federal officials in New York."
Zazi's aunt said Tuesday that her nephew recently visited the Peshawar region of Pakistan - where she said his wife lives. Zazi hopes to bring his wife to the United States, the aunt said.
She said Zazi was born in Pakistan but moved to the United States at an early age and grew up in Queens. He moved to Colorado several months ago, she said.
Associated Press Writers Catherine Tsai, P. Solomon Banda and Don Mitchell in Denver and Tom Hays in New York City contributed to this report.