El Shafee Elsheikh, 33, is accused of being one of four ISIS militants belonging to a cell that operated in Iraq and Syria, which members were nicknamed 'the Beatles' for their British accents. Elsheikh played a leadership role in keeping more than 20 Western hostages captive between 2012 and 2015, prosecutors told the court in Alexandria. Four Americans, journalists James Foley and Steven Sotloff and aid workers Peter Kassig and Kayla Mueller were among the slain hostages.