Testimony at the trial of five men accused of plotting an attack on a U.S. Army base centered Monday on a map of the New Jersey military installation that was found in one suspect's home.

Prosecutors have said the men's possession of the map represents a concrete step in their plans to attack soldiers at Fort Dix and that the map connects the conspiracy to defendant Serdar Tatar, whose father owns a pizza shop that delivered to Fort Dix soldiers. No attack occurred.

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Tatar and the other four defendants are foreign-born Muslims from Jordan, the former Yugoslavia and Turkey in their 20s who spent years in southern New Jersey. They are charged with conspiracy to murder military personnel, attempted murder and weapons offenses. They face life in prison if they are convicted.

Jurors on Monday listened to secret recordings made by government informant Mahmoud Omar that appeared to show Tatar reluctant to give the laminated map to Omar. In the tapes, Omar often refers to the map as "the thing."

They heard Tatar, a newlywed living in Philadelphia, tell Omar that he couldn't get to his father's restaurant to get the map because of car problems or other reasons. When he finally delivered the map, Tatar seemed nervous. "I don't know whether you're FBI," he was recorded saying.

Omar responds with a joke: "I'm George Bush."

An FBI wiretap played in court Monday also showed Tatar's distrust: "You're taking a big risk," Tatar tells co-defendant Mohamad Shnewer, a high school friend. "Out of the blue, he asks me for something like that. It makes you think twice, you know what I'm saying? It's not safe."

On the recordings, what would be done with the map was not directly addressed, although Tatar once suggested that a good target would be the power station that generates electricity to Fort Dix.

But Tatar's defense lawyers pointed to another recording played Monday about how Tatar told a Philadelphia police officer that a man had asked him to get a map of Fort Dix, saying it indicated that he didn't want to be part of a plot.

Prosecutors said he was trying to figure out whether Omar was an informant.

The jury also heard other recordings in which Omar asks Shnewer to set up a meeting with Tatar so they can go over the map, but the meeting never happened. In other conversations, Omar questions Tatar's participation in the plot.

"If he isn't with us, Mohamad, why would he give us the map?" Omar asked.

Defense lawyers are expected to begin cross-examining the informant on Wednesday.