Kayla Jean Mueller (August 14, 1988 – February 6, 2015) was an American human rights activist and humanitarian aid worker from Prescott, Arizona, United States.

After graduating from Tri-City College Prep High School in 2007, she attended Northern Arizona University in Flagstaff to study political science.

[13][14] Doctors Without Borders staff were "flabbergasted" at Mueller's arrival, fearing for her safety, as Syria was dangerous for international aid workers amid a civil war.

[17] The commandos found evidence that the hostages had recently been held there, finding writing on the cell walls and hair believed to be Mueller's, but the refinery was empty.

[21] In August 2015, the New York Times reported that Mueller had been forced into marriage[22][failed verification] to Abu Bakr al-Baghdadi, the leader of ISIS, who raped her repeatedly.

[2] Daniel Rye Ottosen, a Danish freelance photographer and fellow captive, said that the men in the room "...were impressed by the strength that she showed in front of us.

"[27] On February 6, 2015, a media account affiliated with ISIS released a statement claiming that a female American hostage held by the group was killed by one of around a dozen Jordanian airstrikes in Raqqa.

The statement came just days after the release of a video showing the burning alive of a Jordanian fighter pilot, Muath al-Kasasbeh, by ISIS and the subsequent execution of Sajida Mubarak Atrous al-Rishawi and other prisoners of Jordan.

[12] On February 10, 2015, Mueller's family announced ISIS had confirmed her death to them in an e-mail, with three photographs of her dead body, bruised on the face and wearing a black hijab.

[33] Doctors Without Borders then issued a statement (since deleted but archived) to the effect that they felt constrained in their available actions by the complexities of the larger situation and their general lack of expertise in hostage negotiation.

[35] In February 2024 Asma Mohammed, the widow and first wife of ISIS leader Abu Bakr al-Baghdadi, expressed her doubts and skepticism regarding the accuracy of the group’s narrative on the death of Kayla Mueller.

[36] On February 8, 2016, Umm Sayyaf was charged by American prosecutors in Virginia with providing material support to a foreign terrorist organization that resulted in a person's death.

[40] Later, in an interview on The Today Show, Carl Mueller expressed his frustration with the Obama administration over the way it conducted negotiations with their daughter's captors, and their policy of not paying ransom money for hostages.

"[3] Hare Krishna Food for Life, for which Mueller was an active volunteer, stated: "Our prayers go out to her family and friends, a wonderful soul who was making a real difference in many people’s lives.

"[4] An American official cautioned that without proof of Mueller's death, the statement by ISIS could be a ploy to cause the Jordanians and the rest of the American-led coalition to refrain from any heavier airstrikes.

[43][44] He further tweeted: "An old and sick trick used by terrorists and despots for decades: claiming that hostages human shields held captive are killed by air raids.

[49] In October 2015, Mueller became the first person to be posthumously inducted into Northern Arizona University's college of Social and Behavioral Sciences Hall of Fame.

Several aspects of Mueller's life were mentioned, including her college career, her devotion to humanitarian aid and personal faith, as well as her capture, torture and eventual death at the hands of ISIS terrorists.

[54] Carl and Marsha Mueller spoke at the 2020 Republican National Convention, where they described their daughter's ordeal and praised the Trump administration's coordination of the raid that led to the killing of al-Baghdadi.