Islamic State Leader May Have Had U.S. Hostage Executed, Witness Says

WASHINGTON — After the Islamic State declared that Kayla Mueller, a 26-year-old humanitarian worker from Arizona it was holding hostage, was killed in an airstrike in Syria in 2015, her parents became increasingly frustrated with the government’s slow hunt for answers about her death and turned to a former FBI agent for help.


Now, he has unearthed a clue: Mueller may have been executed on the orders of Abu Bakr al-Baghdadi, the slain Islamic State leader, not in a Jordanian...