In the end, the entrapment defense failed, as it has in every other terrorism trial since Sept. 11, 2001. About 2:30 p.m. on Monday, the jury forewoman stood and began reading the verdicts with a wavering voice. “Guilty,” she said, 30 times, as the girlfriend of one of the defendants sobbed in the gallery.

The four men  Onta Williams, Laguerre Payen, James Cromitie and David Williams IV  will be sentenced on March 24. Each could face life in prison. Mr. Cromitie and David Williams were convicted on all eight counts of the indictment. Onta Williams and Mr. Payen, who met the informer late in the investigation, were found not guilty on one of the counts: attempting to kill officers and employees of the United States.

All the men were quiet as the verdicts were read. Mr. Cromitie’s lawyer, Vincent L. Briccetti, patted his client on the shoulder, while a few seats away, David Williams wore a grim smile. After the jury left the room, Mr. Williams’s aunt, Alicia McWilliams-McCollum, stood and yelled obscenities, saying there was no justice. Court officers told her to leave.

In an interview a few hours after the verdict, one juror indicated that the deliberations, which lasted eight days, had been taxing. “We considered that what they did was a serious crime. We also considered that they didn’t have that kind of background,” said the juror, who insisted that his name not be published. “We took our time. We dug deep.”