Boyd has now acknowledged his involvement in supporting and plotting terrorism, pleading guilty in federal court to a pair of charges as prosecutors laid out new details of his activities. The plea provided the government with a crucial conviction against what they have described as a ringleader who guided a Raleigh-area group that sought to wage war against nonbelievers.
Prosecutors said the case illustrated the growing concern of homegrown terrorism.
"The radicalization of Muslims here in our country is a very serious threat," U.S. attorney George Holding said.
More than a half-dozen others have been charged in the case, and most of them were younger than 25 when they were indicted in July 2009, including two of Boyd's sons - Zakariya and Dylan. A trial is scheduled for September. Prosecutors said Boyd is cooperating in the case.
With his once-flowing beard shaven clean and hair slicked back, Boyd tearfully answered a judge's yes-or-no questions before finalizing his guilty plea. He smiled at a few family members in the audience. They declined to comment after the hearing, though his wife has said in the past that he was not involved in terrorism.
Boyd pleaded guilty to conspiring to provide support to terrorists and conspiring to murder, kidnap, maim and injure people. Prosecutors agreed to dismiss several other counts against him. He is to be sentenced in about three months and could serve up to life in prison.
Prosecutors said they had hundreds of recorded phone calls, e-mails and other evidence if the case had gone to trial. They said Boyd had literature in his home or in his e-mail discussing the need for holy war, including some from increasingly prominent figure Anwar al-Awlaki. Holding said Boyd was significantly influenced by al-Awlaki.
National Counterterrorism Center Director Michael Leiter told congressional lawmakers that al-Awlaki's Yemen-based terror organization is the biggest risk to the U.S.
In court, the government focused in part on Boyd's past travels to the Middle East and his claims he fought the remnants of Soviet forces in Afghanistan. Audio tapes played at a previous court hearing included a voice identified as Boyd excitedly telling tales about the fighting.
Because of that stint in Afghanistan two decades ago, prosecutors said Boyd became somewhat of a revered figure in the Raleigh-area Muslim community and that some believers, particularly young ones, turned to him for advice. In turn, Boyd told them of the need to wage violent jihad.
"He did so knowing that he had influence on these young people," said prosecutor John Bowler.
Family members declined to comment while leaving the courthouse.
During an initial court hearing in 2009, federal authorities played audio tapes of Boyd talking about his disgust with the U.S. military, the honor of martyrdom and the need to protect Muslims at all costs. In one, a voice that authorities identified as Boyd says: "I love jihad. I love to stand there and fight for the sake of Allah."
The FBI has said agents seized some two dozen guns and more than 27,000 rounds of ammunition from Boyd's home. Authorities have previously said the men went on training expeditions in the weeks leading up to their arrest, practicing military tactics with armor-piercing bullets on a property in rural North Carolina. They contended he surveyed a Marine Corps base in Virginia and plotted to kill military personnel there.
Joseph S. Campbell, acting special agent in charge of the FBI in North Carolina, said the case should send a message to anyone who may share Boyd's extremist ideology.
"North Carolina and the United States are safer now that Daniel Boyd is no longer in a position to plot against us," Campbell said in a statement.
Boyd grew up in the Washington, D.C., area and converted to Islam as a teenager. He traveled with his family and brother to Pakistan two decades ago.
In 1991, the Boyd brothers were convicted of robbing a bank in Pakistan, but a sentence that included amputations of a hand and foot was overturned.
Associated Press writer Eileen Sullivan contributed to this report from Washington.