Omar has testified that the men never all met as a group to discuss their plans - and that he never discussed a plot with most of them.
"I know the group who were going to participate with us in the operation," he said. "But did I hear from them directly? No."
The five men accused of the plot, all in their 20s at the time of the arrests in May 2007, are foreign-born Muslims who lived for years in the comfortable Philadelphia suburb of Cherry Hill. No plot was carried out.
They're charged with conspiracy to kill military personnel, attempted murder and weapons offenses in a case prosecutors have presented as one of the most frightening examples of homegrown terrorism. If convicted, the men could face life in prison.
Defense lawyers deny the men were seriously planning anything and said Omar tried to make it look like there was a plot. They note that Omar was being paid $1,500 a week to inform for the government.
Most of Omar's recordings involved Mohamad Shnewer, a Jordan-born cab driver who was only 21 when the investigation began in 2006.
On tapes played for jurors Monday, the two men can be heard discussing targets for attacks and even driving to Fort Dix and Dover Air Force Base in Delaware in August 2006. That month and the next, the two men frequently talked about attacking Fort Dix, according to tapes and transcripts that have been presented to the jury.
But by early 2007, Shnewer and Omar were not talking about an attack, defense attorneys said.
Shnewer's lawyer, Rocco Cipparone, showed jurors a transcript of a conversation between the two from March 2007.
Omar asked, "Is it still Fort Dix?"
Shnewer responded that he was thinking about attacking the Army-Navy football game, which had been played in Philadelphia the previous fall.
Cipparone asked Omar whether Shnewer was backing away from an attack on Fort Dix. It was a question that Omar never answered directly.
Two of the suspects - the brothers Shain and Dritan Duka - were arrested while buying a cache of machine guns from Omar in his Cherry Hill apartment.
During that purchase, Omar asked the other men about whether Shnewer would get any guns, according to a surveillance video of it that was played for jurors Monday.
Dritan Duka responded, "He don't know nothing."
Defense lawyers contend that it was Omar who invented the plot, and that he was trying to connect the other men to it. Cipparone has tried to show that even Shnewer, who often talked about the plot, was not serious about it.
Prosecutors say the suspects were very secretive and didn't let Omar in on all the details.