2. Baghdadi is in his forties and claims to be a descendent of the Prophet Mohammad and his Quraysh tribe, one of Islam’s requirements for being a caliph. Beyond that, little is known about him and a lot of information is contested.
Baghdadi descends the stairs of a mosque after giving a speech in his only public appearance on record.
3. Baghdadi is believed to be from the Sunni city of Samarra. Prior to the U.S. invasion of Iraq in 2003, he earned a PhD from the Islamic University of Baghdad and then preached in his hometown, according to analyst Aaron Zelin.
This is an undated picture of Baghdadi released on the Iraqi interior ministry’s official website. Baghdadi’s religious training distinguishes him from al-Qaeda leaders, like Osama Bin Laden, who trained as an engineer, Zelin said.
4. After the U.S. invasion, Baghdadi reportedly helped found a group called Jamaat Jaysh Ahl al-Sunnah wa-l-Jamaah to fight the U.S. occupation. According to Zelin, who cites a biography by a Bahraini scholar, Baghdadi was on the group’s sharia committee.
A U.S. Army soldier takes a blindfolded prisoner into custody during a patrol to search for insurgents in Ramadi in Jan. 2005.
5. In February 2004, he was detained by U.S. officials (under the name of Ibrahim Awad Ibrahim al-Badry) and held in Camp Bucca detention center in Iraq, the New York Times reported in a lengthy profile published Monday.
This is an undated photo of Baghdadi posted by the U.S. State Department. “He was a street thug when we picked him up in 2004,” a Pentagon official told the New York Times. “It’s hard to imagine we could have had a crystal ball then that would tell us he’d become head of ISIS.”
6. The Pentagon says they released Baghdadi in December 2004, believing him to not be a high-level threat, but one Iraqi historian insists he was held for five years. Some believe that is when he further radicalized.
Meanwhile, a group called al-Qaeda in Iraq was growing strong. Baghdadi’s relationship with its leader, Abu Musab al-Zarqawi, killed by the U.S. in 2008, remains unclear. In 2010 Baghdadi was appointed to the top echelons of the group when it announced new leaders. Pictured here are ISIS fighters in Syria in June 2014.
7. Over the years, Baghdadi cultivated relationships with Sunni tribes in eastern Syria and Iraq’s western Anbar and Nineveh provinces, many who had been active in Saddam Hussein’s Baath party and the Sunni insurgency against the U.S. occupation.
8. In 2011, Baghdadi led a team into Syria as the country descended into chaos. Since then, his group has clashed over ideology, tactics and territory with al-Qaeda’s official proxy in Syria, al-Nusra Front, as well as with other Syrian rebel groups.
ISIS fighters in Raqaa, Syria, the self-described capital of the Islamic State.
9. By February 2014, al-Qaeda’s leader Ayman al-Zawhiri officially broke with the now-rogue Baghdadi and ISIS . In the months that followed Baghdadi continued to maintain his hold in eastern Syria — while shifting resources to regain ground in Iraq.
A photo of Al Qaeda leader, Egyptian Ayman al-Zawahiri, in 2011.