Just in:  26-year-old American aid worker Kayla Mueller, held hostage by Islamic State, has been killed, President Obama confirms. 

We are heartbroken to share that weve received confirmation that Kayla Jean Mueller, has lost her life, her parents and brother said on Tuesday.

Supporters of Islamic State had claimed on Friday that she was killed in a Jordanian air strike intended to avenge the burning to death of a captured Jordanian pilot.

Our hearts are breaking for our only daughter, but we will continue on in peace, dignity, and love for her, her parents said.