An American woman held hostage by Islamic State has been identified as 26-year-old aid worker Kayla Mueller.
US officials are working to confirm claims by IS militants that Mueller was killed when Jordanian air strikes hit a building in which she was being held.
Here is what we know about Kayla Mueller
Mueller was captured in Aleppo in August 2013 while working for a humanitarian organisation.
Since graduating from Northern Arizona University in 2009, Mueller's family said she had "devoted her career to helping those in need in countries around the world".
She worked with aid groups in India, Israel and Palestine before returning to Arizona in 2011 to work at an HIV/AIDS clinic and to volunteer at a women’s shelter.
She travelled to Syria in 2012 after seeing the "suffering of the Syrian people".
Mueller spoke of how she helped reunite a Syrian man with his six-year-old son when their refugee camp was bombed.
"For as long as I live, I will not let this suffering be normal," she told the Daily Courier in 2013.
"[I will not let this be] something we just accept.
"It's important to stop and realise what we have, why we have it and how privileged we are. And from that place, start caring and get a lot done."