Abu Bakr al-Baghdadi, ISIS Leader Known for His Brutality, Is Dead at 48. Baghdadi, Abu Bakr al-, Deaths (Obituaries), Islamic State in Iraq and Syria (ISIS), Terrorism, Iraq War (2003-11), Muslims and Islam, Iraq, Syria, Targeted Killings, Sex Crimes, Yazidi (Religious Sect), Mueller, Kayla (1988-2015)