'Hatred truly overwhelmed your humanity,' mother of 1 of El Shafee Elsheikh's victims says, after he's found guilty for role in 'vicious and sadistic' group that killed 4 Americans

British national El Shafee Elsheikh found guilty of belonging to group known for their cruelty to captives, including 4 Americans who were killed

El Shafee Elsheikh one of four UK members of IS cell believed behind killing of journalists James Foley and Steven Sotloff, aid workers Peter Kassig and Kayla Mueller