Negotiating with ISIS

The White House confirmed that 26-year-old Kayla Mueller is dead. She was being held by ISIS after being captured in Syria. Meuller was an aid worker from Arizona. It’s not clear how or when she died. ISIS says she was killed by a Jordanian airstrike. But what efforts were made to try to save Mueller since she was first kidnapped in 2013? And why didn’t they work?