"He also, at times, would say things that you would think that, 'This guy can't be all there,' but I dismissed them as jokes," the former co-worker, Bob Watts, told ABC's "Good Morning America."
Watts said he and Agron Abdullahu worked together at bakery for more than two years and were "like brothers."
"He was an easygoing guy, made you laugh all the time, he was somebody you really enjoyed working with," Watts said.
Abdullahu sometimes made jokes about how the United States couldn't find bin Laden, saying, "U.S., no matter what they do, cannot catch my Uncle Benny," Watts said. He said Abdullahu also showed him bomb recipes that he had in his car.
He said he warned Abdullahu, "you have to watch yourself this day and age, with 9/11, you're going to get yourself into a lot trouble." But Watts said he never saw anything to indicate that his friend hated the country.
"That's what's puzzling me and making my stomach turn knots right now," he said.
Federal authorities said they detained Abdullahu and the other five men because they feared the group was on the verge of carrying out an attack on Fort Dix. The men were arrested Monday night as they tried to buy AK-47 assault weapons, M-16s and other weapons from an FBI informant, authorities said.
"They had training, they had maps, and I think they were very close to moving on this," U.S. Attorney Christopher Christie said Wednesday. "Our view was they had pretty much gotten to concluding the planning phase of this and were looking to obtain heavy weaponry — and if not from us, they were going to try to obtain it elsewhere."
The men — four born in the former Yugoslavia, one from Jordan and one from Turkey — lived in Philadelphia and its suburbs with their immediate and extended families. Three were roofers, one drove a cab, and the two others worked at food stores.
One of the six used his pizza delivery job to gain access to the Army base and scout it out, exposing what may be a security vulnerability, a congressman said Wednesday.
Serdar Tatar was on the fort's approved list of delivery people and given access to the base as part of his job with a nearby pizzeria run by his father, according to a Fort Dix spokeswoman.
Tatar's father, Muslim Tatar, 54, denied that his son had made deliveries to Fort Dix. However, Christie said the younger Tatar spoke of delivering pizzas on tapes made by informants.