(CNN) -- The man at the center of a federal probe into a possible terrorist attack has given writing, fingerprint and DNA samples to federal agents, his attorney said Wednesday.
FBI agents search the apartment of Naijbullah Zazi on Wednesday in connection with a terror investigation.
Naijbullah Zazi, an Afghan national, met with FBI agents at the bureau's Denver, Colorado, office while other agents were searching his apartment and another home in the Denver suburb of Aurora, lawyer Arthur Folsom told CNN. According to law enforcement sources with knowledge of the investigation, the Colorado searches were part of a probe that began with Zazi and led to New York.
Folsom said earlier that Zazi had stayed in an apartment in New York that was raided this week.
As activity increased at the Denver apartment on Wednesday, FBI spokeswoman Kathleen Wright told CNN a search warrant was being executed. At least one law-enforcement dog could be seen, and agents were wearing hazardous material suits.
At least two women were brought out of the apartment. Agents evacuated the complex, which has about 12 units, as a precaution, the FBI said.
Agents also searched a single-family home in the Denver suburb of Aurora later Wednesday, FBI spokeswoman Kathleen Wright said.
On Monday, several apartments in the New York borough of Queens were raided by investigators from the federal Joint Terrorism Task Force, sources close to the investigation said.
They were acting on suspicions that a cell of Afghan nationals associated with a New York-area mosque might be plotting to carry out a terrorist strike in New York. It's believed to be the first time Afghan nationals are suspected of involvement in a terror plot targeting the United States, a source with direct knowledge of the investigation said.
However, FBI director Robert Mueller, asked about the matter Wednesday at a Senate Judiciary Committee hearing, said, "I can say that I do not believe there's imminent danger from that particular investigation -- from what I know of that particular investigation."
Zazi's attorney, Arthur Folsom, told CNN affiliate KUSA that Zazi stayed in one of the apartments that was raided. He said Zazi drove to New York from Denver to sort out a business issue and denied that Zazi has any ties to terrorism
Police stopped the shuttle limousine worker on the George Washington Bridge for what Zazi described as a "random drug stop," but he was cleared, Folsom said.
Later, Zazi's rental car was towed, supposedly for parking violations, Folsom said. While the car was impounded, police asked -- and Zazi granted -- permission to search it and a laptop computer inside. Both were returned to Zazi, who flew back to Denver.
Nothing was found in the Monday raids, according to the source, who added that the targets of the raid may have been "spooked" by publicity or the searches themselves. There also is growing concern that police may have "jumped the gun" and moved in too early, the source said.
However, the probe continues. Additional resources are being brought into New York to support the investigation, the source said.
A law enforcement source earlier said the FBI was looking at locations in the Denver area, where bomb-making materials may have been purchased. The source did not say who may have purchased the materials.
Folsom told KUSA he doesn't know why Zazi chose to drive the rental car to New York and fly back to Denver. But he insists Zazi is eager to answer any questions authorities might have.
"He loves this country," Folsom said. "He loves living here. That's why he brought his family over here. ... We want to clear any air of suspicion that may be surrounding his name at this point."
A man who told CNN he knows Zazi said Zazi stayed at his apartment one night while in New York. The man, who asked not to be identified, said he was taken in for questioning and released during the Monday raids. The man said he is concerned because, after being questioned by authorities, he fears he may not be able to travel to Pakistan on Saturday.
He said he saw Zazi, who moved to Denver about six months ago, at the mosque, and Zazi asked him if he could stay with him. "He's Pashtun," the man said of Zazi. "You can't turn away a fellow Pashtun."
He said he asked Zazi after prayers if he was planning to stay for Taraavi, a longer and more extensive prayer said during Ramadan, but Zazi told him he was tired and went back to the man's apartment. He said Zazi was "probably asleep when I came home." He didn't see Zazi again, and Zazi left the next day, he told CNN.
The building's superintendent, Ramiz Berisha, told CNN that FBI agents were outside the building Tuesday night. He said he is on edge, along with all the building's residents.
The raid involved dozens of agents, some of whom emerged from one building carrying a black document box, according to an eyewitness who lives in one of the buildings that was raided.
CNN's Drew Griffin, Kiran Khalid and Jim Spellman contributed to this report.