9Wants to Know has learned a salesman at Burt Chevrolet, 5200 S. Broadway in Englewood, talked to FBI agents about what happened the day he waited on Zazi. The dealership confirmed on Thursday that the 24-year-old Denver airport shuttle driver came into their showroom on Aug. 20 wanting to look at an advertised 2002 Chevrolet Suburban.

Burt management asked 9NEWS not to name or interview the salesman, because he is part of an ongoing FBI investigation. The dealership's general manager was able to describe generally what happened on the salesman's behalf.

Angelo Chavez, general manager, says his salesman told him Zazi was not a typical customer.

"He [the salesman] was suspicious from the start and being military trained, it raised that alert even more," Chavez said.

Chavez says the salesman is a special forces Army Ranger who has completed two tours of duty in Afghanistan. Chavez says that training came in handy when Zazi made a phone call on his cell phone.

According to Chavez, the salesman said Zazi was speaking a different language.

"Our salesperson is trained in Farsi, and he kind of recognized that from his military experience," Chavez said.

Chavez did not know what was said in that call, but says Zazi quickly changed languages once he noticed the salesman looking at him.

"[He] switched to a different dialect which is called Pashtoon, and that is unique to Afghanistan, and so he knew right away that there is more evidence that something was up," Chavez said.

When the salesman went on a test drive with Zazi, Chavez says he told co-workers to keep their cell phones close in case he needed assistance.

Zazi did not buy the Suburban. He left the dealership and did not return. It is Burt policy to make return calls to customers. On August 31, Burt changed Zazi's status in its computer system to "lost deal" when those calls went unanswered.

When Zazi's name first surfaced in connection with a terror plot against New York City on Sept. 16, Chavez saw his name and picture on an airport TV and remembered he had been in the showroom. He said they contacted the FBI, and agents came out to talk to the salesman. The FBI asked the salesman not to talk specifics about what he told agents.

The FBI was unavailable Thursday evening for comment.

The FBI has visited several businesses in the metro area including home improvement and beauty supply stores, along with U-Haul dealers asking employees to identify names and photographs provided by agents.

The FBI has obtained videotape of Zazi buying beauty supplies containing acetone and hydrogen peroxide at The Beauty Supply Warehouse in Aurora. Sources also tell 9NEWS the FBI has videotape of Zazi and two or three others in the U-Haul dealer at 750 S. Buckley Rd. in Aurora trying to rent trucks.

Zazi pleaded not guilty to one charge of conspiracy to use weapons of mass destruction on Tuesday in New York.