Last week, we reported on news out of Syria that 26 year-old humanitarian aid worker and ISIS hostage Kayla Mueller was killed during a Jordanian air strike. The State Department refused to confirm the message published by ISIS, and experts were quick to point out discrepancies in the group’s claim.

Today, however, Kayla’s family issued a statement to the media confirming the death of their daughter. They didn’t reveal how specifically they knew and were convinced of Kayla’s death, but a representative of the family told the press that they received additional communication from ISIS.

More from NBC News:

“We are heartbroken to share that we’ve received confirmation that Kayla Jean Mueller, has lost her life,” Mueller’s parents, Carl and Marsha, and brother Eric, 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 expressed his “deepest condolences” to Mueller’s relatives.

“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,” he said in a statement calling ISIS a “hateful and abhorrent terrorist group.”

Secretary of State John Kerry said Mueller “represented everything good about the human spirit,” and Secretary of Defense Chuck Hagel said “the world is united in condemning” ISIS’ “murder and imprisonment of innocents.”

“As we join Kayla’s family and loved ones in their grief, we also celebrate her selfless dedication to helping others,” he said in a statement. “Her compassionate spirit will never be forgotten.”

There seems to be little doubt this time surrounding the authenticity of the message. According to ABC News, intelligence officials examined the message and concluded that Kayla was deceased, but could not immediately confirm the “how” or “when.”

Kayla was the last remaining American held by ISIS in Syria; the group is now pushing a series of propaganda films featuring British journalist and hostage John Cantlie.