Read the Heartbreaking Letter That ISIS Hostage Kayla Mueller Sent Home Before She Died

The family of Kayla Jean Mueller, the 26-year-old humanitarian aid worker taken prisoner by the Islamic State group in August 2013, confirmed her death on Tuesday.

"We are heartbroken to share that we've received confirmation that Kayla Jean Mueller has lost her life," her parents said in a statement, according to the Washington Post. "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."

Mueller had traveled to Syria in late 2012 to help refugees caught in the country's civil war.

The family's statement wasn't the end of the story, however. It was accompanied by a heartbreaking — but ultimately hopeful — letter that the Arizona native wrote to her family while in captivity in 2014. Even while confined to a prison cell, Mueller's kindness and grace shone through — further proof that her courageous undertaking was simply part of who she was.

"I have been shown in darkness, light [and] have learned that, even in prison, one can be free," she wrote. "I am grateful. I have come to see there is good in every situation, sometimes we just have to look for it. I pray each day that if nothing else, you have felt a certain closeness [and] surrender to God as well [and] have formed a bond of love [and] support amongst one another. I miss you all as if it has been a decade of forced separation."

Here's the full, hand-written letter, courtesy of the Washington Post:

And here's a transcription, via Vox

Everyone,

The news of her death, which was confirmed by the FBI, comes just days after the Islamic State group alleged that Mueller had been killed in a Jordanian airstrike in Syria in retaliation for the group's gruesome execution of a Jordanian pilot. Despite the claim, her family had held out hope that she was still alive due to a lack of evidence provided by the militant Islamist group.  

President Barack Obama offered his condolences on Tuesday, noting that Mueller had dedicated her life to helping others. 

"Kayla Mueller used these freedoms she so cherished to improve the lives of others," the statement read.

ABC/Mueller Family