The US unsealed a criminal complaint Saturday charging a Saudi-born Canadian, Mohammed Khalifa, 38, with providing material support to the terror group "Islamic State" (IS) following his capture by Syrian Democratic Forces in 2019.

Khalifa had told his mother that he was moving to Egypt, but, in fact, he traveled to Turkey before crossing into Syria in August of 2013.

In November 2013, he pledged allegiance to the terror group IS. By April of 2014, he was appointed to the propaganda arm of IS where he worked on producing slick videos, including of executions of US and other foreign nationals, due to his fluency in English and Arabic.

Using the aliases Abu Ridwan al-Kanadi and Abu Muthanna al-Muhajir, "Khalifa allegedly served as a lead translator in ISIS's propaganda production and the English-speaking narrator on multiple violent ISIS recruitment videos," the US Department of Justice said in a statement, using another name for the terror group. 

Khalifa's 5-year run as a top IS propagandist

In his years with IS, Khalifa worked on recruiting foreigners to move to territory controlled by the terror group and instigating and inspiring others to commit attacks in Western countries not controlled by IS.

Khalifa narrated two of the most violent and influential propaganda videos, Flames of War: Fighting Has Just Begun, released in September of 2014, and Flames of War II: Until the Final Hour, which dropped in November of 2017, when the group was rapidly losing territory.

The US Department of Justice said in a statement the Flames of War videos, "depict glamorized portrayals of IS and its fighters as well as scenes of violence, including depictions of unarmed prisoners being executed."  

Some of the propaganda videos IS released while Khalifa was a prominent figure in the media arm include beheadings of Americans James Foley, Steven Sotloff and Peter Kassig, British hostages David Haines and Alan Henning, and Japanese national Kenji Goto.

The criminal complaint makes clear that the US government is not making public all the evidence it has in the case against Khalifa.

The Department of Justice notes that Khalifa is one of many foreign fighters who was inspired to violent jihad by Anwar al-Awlaki, a Yemeni-born US national who became a significant figure in al-Qaeda's propaganda, including in the production of Inspire Magazine.

Al-Awlaki was killed in a drone strike in Yemen in 2011. Posthumously al-Awlaki remains a major figure in the recruitment of foreign fighters due to his charismatic presentations and fluent English, with his name coming up over the years in numerous indictments and court cases of accused terror suspects in the US.

Why is Khalifa being charged now?

While the Syrian Democratic Forces (SDF) captured Khalifa in January 2019 on the battlefield, they have held him since.

The New York Times reports that Khalifa was handed over to the FBI earlier this week and subsequently flown to Virginia, where he was charged.

Media outlets, including the Canadian Broadcasting Corporation and The New York Times, interviewed him while he was held in Syria, as did the FBI, according to the criminal complaint. The criminal complaint notes the FBI made him aware of his rights during their interview with Khalifa in Syria.

In a 2019 interview with The New York Times, Khalifa disavowed playing an active role in the violent atrocities committed by IS, claiming that "I was only the voice."

His battlefield capture after reportedly throwing grenades at opposing combatants, however, suggests that this may not have been the full truth.

Khalifa is the first foreign fighter to be prosecuted in the US under the Biden administration.

Associated Press contributed to this report.