President Donald Trump announced on Sunday that US Special Forces killed Abu Bakr al-Baghdadi, the founder and leader of the Islamic State, during a raid in the Idlib province of Syria on Saturday.
"Last night, the United States brought the world's number one terrorist to justice," Trump announced at a nationally-televised Sunday morning press conference. "Abu Bakr al-Baghdadi is dead."
The self-declared caliph of the Islamic State in Iraq and Syria, Al-Baghdadi, 48, was instrumental in building the Islamic State into one of the most potent terrorist groups in history that, at its height, controlled a territory the size of Great Britain.
The secretive jihadist was born as Ibrahim Awad Ibrahim Ali al-Badri in a village in central Iraq to a Sunni Muslim family and was educated in the city of Samarra. His family claimed to descend from the Prophet Muhammad's tribe, which made it possible for al-Baghdadi to later become the leader of the Islamic caliphate.
He took to a conservative interpretation of Islam early in his life and received an undergraduate degree from the Shariah College of University of Baghdad in 1996. Three years later, he earned a master's degree in Koranic recitation from the Saddam University for Islamic Studies.
He interrupted his doctorate work to join the fight against American forces after the US invasion of Iraq in 2003.
Al-Baghdadi, whose nom de guerre was then "Abu Dua," was arrested at the home of his parents-in-law near Falluja in January 2004. His brother-in-law, who'd been fighting the American invasion of Iraq, was the target of the raid. Al-Baghdadi was ultimately detained at Camp Bucca, which housed tens of thousands of Iraqis in communal tents, for 11 months.
"He was a street thug when we picked him up in 2004," an anonymous Pentagon official told The New York Times in 2014. "It's hard to imagine we could have had a crystal ball then that would tell us he'd become head of ISIS."
Experts say Al-Baghdadi's stay at the detention center helped facilitate his radicalization and served as a planning headquarters for ISIS. He was chosen as a leader by fellow prisoners in the camp, making alliances with other Sunni prisoners and former Iraqi Baathists.
It was there that al-Baghdadi met and became a follower of Jordanian jihadist, Abu Musab al-Zarqawi, who would go on to lead al-Qaeda in Iraq.
"We could never have all got together like this in Baghdad, or anywhere else," Abu Ahmed, a jihadist imprisoned with al-Baghdadi at Camp Bucca, told The Guardian in 2014. "It would have been impossibly dangerous. Here, we were not only safe, but we were only a few hundred meters away from the entire Al Qaeda leadership."
More broadly, many argue that the US invasion and occupation of Iraq in the early 2000s motivated and fueled al-Baghdadi's rise.
"He is Iraqi to the core, and his extremist ideology was sharpened and refined in the crucible of the American occupation," Tim Arango and Eric Schmitt of The Times wrote of al-Baghdadi in 2014. "The American invasion presented Mr. Baghdadi and his allies with a ready-made enemy and recruiting draw. And the American ouster of Saddam Hussein, whose brutal dictatorship had kept a lid on extremist Islamist movements, gave Mr. Baghdadi the freedom for his radical views to flourish."
The US military released him in December 2004.
For years, very little was known about al-Baghdadi. He served as a religious adviser to al-Qaeda terrorist cells in Iraq. As US forces dealt significant blows to al-Qaeda's leadership, the spiritual instructor rose to become the top leader in 2010 of what was then the Islamic State of Iraq.
The Arab Spring, which began in late 2010, and the civil war in Syria, which began in early 2011, provided his weakened group with new motivation, fighters, and weapons. His fighters eventually captured the eastern Syrian city of Raqqa.
By the early summer of 2014, Islamic State forces shocked the world by seizing control of one-third of Iraq, including the country's second-largest city, Mosul, and half of Syria.
In his only filmed public address, al-Baghdadi declared the founding of the caliphate in a speech in a Mosul mosque in 2014, telling his followers, "Know that today you are the defenders of the religion and the guards of the land of Islam."
There were multiple reports that al-Baghdadi was killed or injured in various attacks over the last few years, but all of them proved false.
The Islamic State, also known as ISIS, ultimately recruited tens of thousands of fighters from 100 countries, according to The Times. It carried out or inspired terrorist attacks that have killed thousands in countries around the world and became perhaps best known for its extraordinarily brutal, gruesome murder and torture of its prisoners, including Americans.
The group used the internet to build networks of support around the world, enforced extreme religious rules inspired by Islamic theocracies in the Middle Ages, and brutally targeted religious minorities, including the Yazidis.
Al-Baghdadi personally promoted and participated in the systematic rape of women who ISIS considered non-believers, including an American ISIS captive, Kayla Mueller, who al-Baghdadi kept as one of several of his sex slaves. ISIS reported Mueller was killed in a Jordanian airstrike in 2015.
While the Islamic State has lost control of virtually all of its territory, there remain widespread fears that the group will re-emerge or morph into a new terrorist movement, and that its ideas will not die along with its leaders.