The brothers are the sons of, Daniel Boyd, the man who is labeled the rig leader of the operation.
The trial began two weeks ago at the federal courthouse in New Bern and prosecutors may be at the end of their witness list.
Boyd testified last week. His sons, Zach and Dylan, testified Wednesday.
The brothers and their father agreed to plead to a reduced number of terror charges in exchange for their testimony. Dylan told jurors his father became more controlling and a zealous Muslim after he nearly died of hepatitis in 2003.
Dylan said his father sometimes waffled. "He had strong views of ideology that called for violence but sometimes talked of peace," he testified.
He said the same of the three Raleigh men on trial -- Omar Hassan, Ziyad Yaghi and Hysen Sherifi. But Dylan said there was a time when Sherifi said he would consider a suicide mission.
He told jurors, "He [Sherifi] said he could take a van loaded with explosives to a military installation in America."
A 2009 raid at the Boyd's Johnston County home uncovered weapons, ammunitions, and jhadist propaganda, according to the FBI. Investigators have said the group was considering targets that included the Marine based at Quantico, Va. as well as countries oversees.
One of the terror suspects remains a fugitive and is believed to be in the Middle East. Another will be tried separately.
The Boyds' fate is in the hands of a judge who they hope will go easier on them because of their cooperation with prosecutors.