In February 2004, U.S. troops brought a man named Ibrahim Awad Ibrahim al-Badry to Abu Ghraib in Iraq and assigned him serial number US9IZ-157911CI. The prison was about to become international news, but the prisoner would remain largely unknown for the next decade.

At the time the man was brought in, Maj. Gen. Antonio Taguba was finalizing his report on allegations of abuse at Abu Ghraib’s Hard Site — a prison building used to house detainees singled out for their alleged violence or their perceived intelligence value. Just weeks later, the first pictures of detainee abuse were published on CBS News and in the New Yorker.

Today, detainee US9IZ-157911CI is better known as Abu Bakr al-Baghdadi, the leader of the Islamic State. His presence at Abu Ghraib, a fact not previously made public, provides yet another possible key to the enigmatic leader’s biography and may shed new light on the role U.S. detention facilities played in the rise of the Islamic State.

Experts have long known that Baghdadi spent time in U.S. custody during the occupation of Iraq. Previous reports suggested he was at Camp Bucca, a sprawling detention facility in southern Iraq. But the U.S. Army confirmed to The Intercept that Baghdadi spent most of his time in U.S. custody at the notorious Abu Ghraib.

Read the rest at The Intercept.