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A suspected terrorist linked to the 2012 Benghazi terror attack that killed four Americans has been captured inside Libya by U.S. forces and currently is en route to the United States, Fox News has learned.

Sources told Fox News that the suspect, Ansar al-Sharia commander Ahmed Abu Khattala, was captured Sunday during a joint U.S. military and law enforcement operation, and will face prosecution in the United States.

President Obama signed off on the mission on Friday night, Fox News is told. Khattala was captured south of Benghazi by U.S. special operators and is on his way to the U.S. aboard a Navy ship.

Khattala was long thought to be one of the ringleaders of the deadly attack, in which U.S. Ambassador Chris Stevens and three other Americans died. He had openly granted media interviews since the 2012 attack, but until now evaded capture.

The capture marks the first time the United States has caught one of the suspects in the 2012 assault.

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"He didn't know what hit him," one source told Fox News of the capture. According to sources, there was no firefight -- a small Special Forces team with one FBI agent took part in the mission.

White House and Pentagon officials publicly confirmed the capture late Tuesday morning. At an event in Pittsburgh, President Obama also said the capture is a "message to the world" about what happens when Americans are attacked.

"No matter how long it takes, we will find those responsible and we will bring them to justice," Obama said. In a written statement, the president thanked the "painstaking efforts of our military, law enforcement and intelligence personnel," and said the suspect would "now face the full weight of the American justice system."

Pentagon Press Secretary Rear Adm. John Kirby called Khattala a "key figure in the attacks on U.S. facilities in Benghazi." He said there were no civilian casualties in the weekend operation, and all U.S. personnel have "safely departed" Libya.

The administration has faced sustained criticism from some in Congress and the families of the victims over the fact that no one had been brought to justice since that day in 2012.

State Department official Sean Smith, and CIA contractors Tyrone Woods and Glen Doherty were also killed during the attack. Khattala's capture came 642 days later.

With Khattala set to face prosecution in a U.S. court, the administration already is being pressed to hold off on reading him his Miranda rights until he is interrogated.

"I am pleased that Khattala is finally in U.S. custody, and I am grateful for the military, intelligence, and law enforcement professionals who helped capture him," Sen. Kelly Ayotte, R-N.H., said in a statement, adding: "Rather than rushing to read him his Miranda rights and telling him he has the right to remain silent, I hope the administration will focus on collecting the intelligence necessary to prevent future attacks and to find other terrorists responsible for the Benghazi attacks."

Some Republican lawmakers, including Sens. Marco Rubio of Florida and Ted Cruz of Texas, said the suspect should be sent to Guantanamo Bay.

U.S. officials, without saying whether the suspect has been read his Miranda rights, said he has undergone an "intelligence interrogation."

Khattala faces three counts in the federal complaint against him, which was filed in the U.S. District Court for the District of Columbia.

They are: killing a person in the course of an attack on a federal facility; providing or attempting to provide support to terrorists resulting in death; and using or carrying a firearm in relation to a crime of violence.

Attorney General Eric Holder said the Justice Department retains the option of adding additional charges.

"Our nation's memory is long and our reach is far," Holder said in a statement, adding: "Even as we begin the process of putting [Khattala] on trial and seeking his conviction before a jury, our investigation will remain ongoing as we work to identify and arrest any co-conspirators."

Khattala, until this past weekend, had loomed as an almost taunting presence. A month after the attack, he admitted to Fox News that he was at the scene of the attack, though claimed he did not plan it. At the time, he claimed he was just directing traffic and looking after fellow militia members guarding the complex.

He offered no remorse, though, for the killing of four Americans. At the time, he said he had not yet been contacted by U.S. officials.

At briefings on Tuesday afternoon, State and Defense department officials were questioned repeatedly on why reporters were able to get in touch with Khattala after the attack but U.S. forces apparently were not.

"Terrorists go to great lengths to evade capture, and it can be a complicated process trying to get at them," Kirby said. "What matters is ... that we got him."

Fox News' Ed Henry, Bret Baier, Jennifer Griffin, Greg Palkot, Jake Gibson and Lucas Tomlinson contributed to this report.