Though a comprehensive understanding of ISIS' network of operatives remains elusive, some of the leadership and individuals who have carried out acts of terror around the world have been identified. At least 12 who served or continue to serve as the top leaders of ISIS spent time at Camp Bucca, known as the largest, and one of the toughest, American prisons in Iraq.
Ibrahim Awad Ibrahim Ali al-Badri al-Samarai
Abu Bakr al-Baghdadi
Al-Baghdadi is the caliph (leader) of ISIS. He was born in Samarra, and educated in Islamic history and, possibly, Sharia law at the University of Baghdad. He's now in his early 40s and married to possibly two wives, with at least a couple of kids.
U.S. forces detained him as a "civilian internee" in what the Department of Defense says was his hometown of Fallujah, and was imprisoned Feb. 4, 2004 at Camp Bucca, a U.S. prison camp, in Umm Qasr, Iraq. He was released from U.S. custody in early December. Soon after, he may have joined Abu Musab al-Zarqawi's Mujahideen Shura Council, an umbrella organization of Sunni insurgent groups that included al Qaeda in Iraq. He rose in power and was third in command when the top two leaders of ISIS in Iraq were killed in early 2010.