Kayla Jean Mueller, a 26-year-old American woman held by Islamic State of Iraq and Syria (ISIS) militants, has been confirmed dead, her parents and the Obama administration said Tuesday.
CBS News national security correspondent David Martin reports that ISIS sent the family an e-mail telling them their daughter was dead and including a picture. The picture showed that she had died "recently" but the cause and exact date of her death were inconclusive. The U.S. intelligence community was then able to verify the photo.
"We are heartbroken to share that we've received confirmation that Kayla Jean Mueller, has lost her life," Carl and Marsha Mueller said in a statement. "Kayla was a compassionate and devoted humanitarian. She dedicated the whole of her young life to helping those in need of freedom, justice, and peace."
President Barack Obama said that Mueller, who was an aid worker who assisted humanitarian organizations working with Syrian refugees, "epitomized all that is good in our world."
"No matter how long it takes, the United States will find and bring to justice the terrorists who are responsible for Kayla's captivity and death," the president said.
Mueller, of Prescott, Arizona, is the fourth American to die while being held by ISIS militants. Three other Americans - journalistsJames Foley and Steven Sotloff, and aid worker Peter Kassig - were beheaded by the group.
Journalist Austin Tice, of Houston, Texas, disappeared in August 2012 while covering Syria's civil war. It's not clear what entity is holding him, but it is not believed to be ISIS or the Syrian government, his family has said.
Mueller was taken into captivity in August 2013 while leaving a hospital in Syria. Her identity was long kept secret out of fears for her safety.
On Friday, ISIS claimed that Mueller died in a Jordanian airstrike. Jordan, which has launched a barrage of strikes in recent days in retaliation for the gruesome killing of one of its pilots at the hands of the militants, disputed that report and the White House said at the time that it had seen no evidence to corroborate the ISIS claims.
Mueller had been working in Turkey assisting Syrian refugees, according to a 2013 article in The Daily Courier, her hometown newspaper. She told the paper that she was drawn to help with the situation in Syria.
"For as long as I live, I will not let this suffering be normal," she said. "It's important to stop and realize what we have, why we have it and how privileged we are. And from that place, start caring and get a lot done."
According to the newspaper, Mueller had been working with the humanitarian aid agency Support to Life, as well as a local organization that helped female Syrian refugees develop skills.
A 2007 article about Mueller from the same newspaper said she was a student at Northern Arizona University and was active in the Save Darfur Coalition. A statement from the office of Sen. John McCain, R-Ariz., said Mueller graduated in 2009 and had worked to help people in need in India, Israel, the Palestinian territories and in Arizona.
Mueller's family said, "We are so proud of the person Kayla was and the work that she did while she was here with us. She lived with purpose, and we will work every day to honor her legacy."
"She knew where she was headed," family friend Todd Geiler said. "She knew what she wanted to do. There was compassion and caring for those less fortunate. She always wanted to help somebody in need."