U.S. special operations forces conducted a raid in Libya this weekend that captured a militant believed to have played a key role in the deadly 2012 attack on the Benghazi consulate, according to U.S. officials. That attack killed Ambassador Christopher Stevens and three other American.

According to an official, the militant captured by elite special operations forces this weekend was Mustafa al-Imam. He was transferred to a ship offshore at some point after the capture and may still be aboard, another official said.

The plan is to transfer him back to the U.S. for prosecution in federal court, according to an official.

"Yesterday, on my orders, United States forces captured Mustafa al-Imam in Libya," said President Donald Trump in a statement. "Because of this successful operation, al-Imam will face justice in the United States for his alleged role in the Sept. 11, 2012, attacks in Benghazi, which resulted in the deaths of Ambassador Christopher Stevens, Glen Doherty, Sean Smith, and Tyrone Woods -- four brave Americans who were serving our country."

The statement continued: "Our memory is deep and our reach is long, and we will not rest in our efforts to find and bring the perpetrators of the heinous attacks in Benghazi to justice."

"I want to thank our law enforcement, prosecutors, intelligence community, and military personnel for their extraordinary efforts in gathering evidence, interviewing witnesses, and tracking down fugitives associated with the attack, capturing them, and delivering them to the United States for prosecution," said the statement.

Secretary of State Rex Tillerson also issued a statement praising the militant’s capture.

“The Department of State family continues to mourn the loss of Ambassador Chris Stevens, Glen Doherty, Sean Smith, and Tyrone Woods, and we will spare no effort to ensure that justice is served for these dedicated Americans and public servants,” said Tillerson. “I spoke with some of their family members to underscore the U.S. government’s unwavering support.”

"Today the Department of Justice announces a major step forward in our ongoing investigation as Mustafa al-Imam is now in custody and will face justice in federal court for his role in the attack. I am grateful to the FBI, our partners in the intelligence community and the Department of Defense who made this apprehension possible," said Attorney General Jeff Sessions in a statement.

"Al-Imam is in U.S. custody, and upon his arrival to the U.S. he will be presented before a federal judge in Washington, D.C.," said a Justice Department statement.

The 46-year-old Mustafa al-Imam is charged in a recently unsealed three-count criminal complaint filed on May 19, 2015, in the U.S. District Court for the District of Columbia.

"Al-Imam is charged with 'killing' a person in the course of an attack on a federal facility involving the use of a firearm and dangerous weapon and attempting and conspiring to do the same," said the Justice Department statement.

He is also charged with "providing and conspiring to provide material support to terrorists resulting in death" and "discharging, brandishing, using, carrying and possession of a firearm during and in relation to a crime of violence."

Complete details of this weekend's secret raid into Libya are still unknown. Typically "snatch and grab" missions like this are conducted by elite special operations teams like Delta Force or SEAL Team Six.

In July 2014, the elite Delta Force captured Ahmed Abu Khatallah at his home in Benghazi. The militia leader was an alleged ringleader of the Benghazi attack two years earlier.

Khatallah was transferred to a U.S. Navy ship offshore and was transported to the U.S. for prosecution in a federal court.

His trial began earlier this month in Washington, D.C.