Kayla Jean Mueller, an American prisoner held by ISIS, was confirmed dead on Tuesday, the Washington Post's Adam Goldman reports. The Post and a number of other outlets have also published an absolutely heartbreaking letter Mueller sent to her family from captivity last year.

"I have come to see there is good in every situation, sometimes we just have to look for it," she told her family. "Please be patient, give your pain to God. I know you would want me to remain strong. That is exactly what I am doing. Do not fear for me, continue to pray as will I + by God's will we will be together soon."

The circumstances of Mueller's death are still unclear. Last week, ISIS claimed that Mueller was killed in a Jordanian airstrike. But ISIS has strong incentives to lie here and has lied in the past.

Mueller disappeared in Aleppo, Syria, in 2013. She was there as an aid worker helping innocent victims of the Syrian civil war. "For as long as I live, I will not let this suffering be normal. (I will not let this be) something we just accept," Mueller said in a 2013 address to the Kiwanis Club in her hometown of Prescott, Arizona, as reported by Prescott's Daily Courier newspaper. "When Syrians hear I'm an American, they ask, 'Where is the world?' All I can do is cry with them, because I don't know."

Mueller's letter, which the Post says was released by her family, was full of the same grace and humanity.

"If you could say I have 'suffered' at all throughout this whole experience it is only in knowing how much suffering I have put you all through," Mueller wrote in the 2014 letter. "I will never ask you to forgive me as I do not deserve forgiveness."

Here's the full text of the letter, based on the Post's transcription (paragraph breaks added for readability). You can read the original handwritten version over at The Post: