Abu Khatallah faces 18 charges related to the deadly violence that began on September 11, 2012, including the murder of an internationally protected person, providing material support to terrorists and destroying US property while causing death.
During the attack, assailants armed with automatic weapons and rocket-propelled grenades first blasted through the main diplomatic mission before setting it ablaze, according to 2014 court papers.
Stevens and State Department information officer Sean Smith died there. A coordinated mortar assault on a nearby annex killed security officers Tyrone Woods and Glen Doherty, both CIA contractors and former US Navy SEALs.
"The defendant's participation in the attack was motivated by his extremist ideology," prosecutors said in the documents, which also alleged that Abu Khatallah "voiced concern and opposition to the presence of an American facility in Benghazi" days prior to the attack.
Abu Khatallah -- the only Benghazi suspect currently in US custody
-- has pleaded not guilty
, and his case will be heard by a jury at a US District Court in Washington starting Monday.
In 2016, the Justice Department announced it would not pursue the death penalty against Abu Khatallah meaning he will face a maximum sentence of life in prison if convicted.
Beyond determining Khatallah's fate, the high-profile trial will mark the latest chapter in the debate over how to handle foreign terrorism suspects.
The Obama administration argued it was most effective to prosecute suspected foreign terrorists in civilian courts rather than holding them without trial in detention centers like Guantanamo Bay.
But other lawmakers have said it is best to interrogate terror suspects without reading their Miranda rights in order to extract intelligence.
Shortly after the White House announced Abu Khatallah's capture, Republicans like Florida Sen. Marco Rubio criticized the Obama administration because they believed the alleged terrorist should go through a military tribunal at Guantanamo Bay instead of being tried in a federal court.
"If they bring him to the United States, they're going to Mirandize this guy, and it would be a mistake for the ages to read this guy his Miranda rights," Republican Sen. Lindsey Graham of South Carolina has said.
But the Justice Department defended the decision at the time, saying that they had successfully tried a number of terrorists domestically and that no new captives have gone to the Guantanamo Bay detention facility in years.
Coming in the midst of a US presidential campaign, the Benghazi assault ignited a political firestorm -- the effects of which still linger five years later.
Republican critics of former President Barack Obama and then-Secretary of State Hillary Clinton seized on the vulnerability of the US compound on the anniversary of the 9/11 attacks to accuse the administration of failing to provide proper security.
After a two-year investigation, House Republicans released a more than 800-page report
in June 2016 that faulted the Obama administration for security lapses that led to the deaths of four Americans, but contained no revelations deemed likely to further damage Hillary Clinton. The report painted a picture of a perfect storm of bureaucratic inertia, rapidly worsening security in Libya and inadequate resources in the months that led up to the attack.
Republicans also launched allegations of a politically inspired coverup after the White House initially appeared to blame the unrest on spontaneous protests against an anti-Muslim video made in America.
Such protests occurred in other cities in the region that day, but US officials later acknowledged the Benghazi attack was an organized assault instead of simply a spur-of-the-moment demonstration that spiraled out of control.
Clinton denied allegations of a coverup and the claims were later determined to be unproven.
GOP members scrutinized how Clinton handled the matter ahead of her failed 2016 presidential bid. She oversaw US diplomacy at the time as secretary of state, resulting in questions about her responses and decisionmaking in addition to grilling by lawmakers during testimony on Capitol Hill.
Who is Ahmed Abu Khatallah?
A slender man with long gray hair and a shaggy gray beard, Abu Khatallah emerged from years in prison under the regime of former Libyan leader Moammar Gadhafi to form an Islamist militia and later became associated with Ansar al-Sharia, a group US officials blamed for the 2012 attack.
Believed to be in his 40s, Abu Khatallah became the face of the militant attack and a top target for the US after he cultivated a celebrity profile in its wake, meeting with journalists and granting interviews.
Those appearances prompted criticism of the Obama administration from Republican lawmakers over how long it was taking to arrest the alleged attackers.
In a 2013 interview
with CNN's Arwa Damon, Abu Khatallah suggested he had no role in the attack.
"I didn't know where the place was," he said, aided by a translator. "When I heard, we went to examine the situation. When we withdrew and there was shooting with medium guns and there were RPG's in the air and people panicked, we tried to control traffic."
But prosecutors have since painted a drastically different picture, claiming he was a key figure in the larger conspiracy that ultimately led to the deaths of four Americans.
New details about raid to capture Abu Khatallah
Witness testimony during a pre-trial evidentiary hearing in May 2017 revealed new details about efforts to capture and interrogate Abu Khatallah -- a process that the defense unsuccessfully argued was a violation of his rights.
While a federal judge ultimately rejected the defense's request to suppress statements Abu Khatallah made to interrogators while being transported from Libya to the US, the hearing provided a rare look into how terrorism suspects are handled before stepping foot in an American courtroom or provided a lawyer.
Abu Khatallah was seized by US special operations forces in June 2014 after intelligence assets lured him to a beach side villa near Benghazi.
Upon entering the villa, Abu Khatallah was ambushed by US commandos wearing plain clothes -- sustaining several superficial injuries to his face and hands during a short struggle, according to testimony from an Army doctor assigned to monitor the capture mission.
Abu Khatallah was carrying a pistol in a hip holster at the time of his capture, the sole FBI agent present during the raid testified in May.
Once in custody, Abu Khatallah was led under the cover of darkness to a small boat by the eight-person capture team and taken to the USS New York amphibious transport vessel anchored off the coast of Libya.
During the two-hour boat ride to the USS New York, Abu Khatallah was heard uttering an Arabic phrase that was translated to mean "Why me God, why me," according to the FBI agent.
After boarding the Navy ship, Abu Khatallah was informed of his rights under the Geneva Conventions and inspected by an Army doctor.
He was then placed in an eight-by-seven-foot detention pod on the ship that included a latrine, mattress, and religious items like a Koran, according to testimony.
The defense suggested that Abu Khatallah was subjected to a "slow boat to DC strategy" to deliberately maximize interrogation time during his 13-day voyage to the US aboard the USS New York.
But prosecutors argued that his rights were upheld as he was questioned by two sets of interrogators -- an intelligence gathering team and a separate FBI unit tasked with collecting criminal evidence.
Intelligence agents conducted a five-day interrogation without reading Abu Khatallah his Miranda rights -- he was questioned again by FBI agents two days later, according to testimony from members of both teams.
While the FBI interrogators did read him the Miranda rights before questioning, defense attorneys argued that Abu Khatallah's statements should be excluded from courtroom evidence despite waiving his rights and continuing to answer questions about the Benghazi attack without a lawyer present.
Despite protests from the defense, a federal judge ruled in August that the statements made by Abu Khatallah while on the USS New York will be permitted in court as evidence.
Abu Khatallah "was treated respectfully and humanely while in custody; he was not subject to threats or promises of any kind; and his interview sessions were broken up frequently with time for meals, rest and prayer," the judge wrote.