Ahmed Abu Khattala was scheduled to appear before a magistrate judge, according to the U.S. attorney's office. He is charged in connection with the assaults on the U.S. diplomatic compound in the eastern Libyan city on Sept. 11, 2012, that killed the U.S. ambassador and three other Americans.
U.S. special forces captured Abu Khattala in Libya two weeks ago, marking the first breakthrough in the investigation. Officials had been questioning Abu Khattala aboard a Navy ship that transported him to the United States.
Abu Khattala was flown early Saturday by military helicopter from the ship to a National Park Service landing pad in the city's Anacostia neighborhood, according to a U.S. official who was not authorized to discuss the transfer publicly and spoke on condition of anonymity.
The prosecution reflects the Obama administration's stated position of trying suspected terrorists in the American criminal justice system even as Republicans call for Abu Khattala and others to be held at the U.S. detention facility in Guantanamo Bay, Cuba.
Critics say suspected terrorists don't deserve the legal protections afforded by the American court. The administration considers the civilian justice system fairer and more efficient.
A criminal complaint filed last year and unsealed after Abu Khattala's capture charges him with terror-related crimes. They include killing a person during an attack on a federal facility; that crime can be punishable by death.
At the initial hearing, the government was expected to outline the charges against him. He almost certainly will remain in detention while the Justice Department seeks a federal grand jury indictment against him.
The violence in Libya on the 11th anniversary of the Sept. 11 attacks on the World Trade Center and the Pentagon quickly became a political controversy at home.
Republicans accused the White House, as the 2012 presidential election neared, of intentionally misleading the public about what prompted the attacks. The White House said Republicans were politicizing a national tragedy.
Abu Khattala was a prominent figure in Benghazi's circles of extremists. He was popular among young radicals and lived openly in the eastern Libyan city, spotted at cafes and other public places, even after the Obama administration publicly named him as a suspect.
He is accused of being a member of the Ansar al-Shariah group, the powerful Islamic militia that the U.S. believes was behind the attack.
He acknowledged in an interview with The Associated Press in January that he was present during the storming of the U.S. mission in Benghazi. But he denied involvement in the attack, saying he was trying to organize a rescue of trapped people.
In the attack, gunmen fired rocket-propelled grenades and stormed the mission, with many waving the black banners of Ansar al-Shariah.
The compound's main building was set ablaze. Ambassador Chris Stevens suffocated to death inside and another American was shot dead.
At the time, several witnesses said they saw Abu Khattala directing fighters at the site.
Later in the evening, gunmen attacked and shelled a safe house, killing two more Americans. No evidence has emerged that Abu Khattala was involved in the later attack.
Abu Khattala is one of just a few cases in which the administration has captured a suspected terrorist overseas and interrogated him for intelligence purposes before bringing him to federal court to face charges.
Those cases include Osama bin Laden's son-in-law, Sulaiman Abu Ghaith, who was arrested in Jordan in March 2013 and turned over to U.S. agents. A jury in New York City convicted him in March of conspiring to kill Americans.
AP National Security Writer Robert Burns contributed to this report.
U.S. attorney's office: http://tinyurl.com/pdakxfv