Among her torturers also was the notorious Jihadi John, the British ISIS leader shown in videos beheading American James Foley and many others.

British intelligence, the Muellers learned, for months in 2014 tracked this elite entourage that included Kayla and other hostages in northern Syria. They gave the United States the location of a building plus its interior layout in Raqqa where about two dozen Western hostages were held. The U.S. government was slow to mount the Delta Force operation, and when it did—seven weeks later on July 4, 2014—the hostages had been moved elsewhere. ISIS intermediaries told the Muellers in an email the failed attack was “lame.”

What we know now is the missed opportunities of 2014 had monumental consequences: Had the United States captured or killed Baghdadi and some in his inner circle, ISIS might never have mounted its assault into Iraq, which took place that summer. It might never have captured and killed tens of thousands of Yazidis in Iraq and overrun scores of Christian towns. It might not have set up slave markets inside Mosul where thousands of women were trafficked for years, forced to endure what Kayla Mueller endured.

Four years into a nearly fruitless mission for closure on their daughter’s death, the Muellers learned something completely surprising: Kayla might be still alive.

Early this year they received reports from “credible sources” inside Syria, they say. For several years rumors had made their way to the family, sightings suggesting Kayla may have been in a prison in Mosul, indications she could be in northern Syria with thousands of other ISIS captives as the group’s territory shrank to Deir Ezzor and then to the small town of Baghuz on the Euphrates River. As fighting intensified, such reports came with added urgency and believability.

Based on the new information, the Muellers prepared flyers containing Kayla’s photo and sent them this year into Syria and Turkey during the February offensive by U.S. and Syrian Democratic Forces to defeat ISIS at Baghuz.

Distributed in Arabic and English, the leaflets offered a reward for “new and verifiable information about what happened to our daughter.” Syrian and American workers in the region, not named for security reasons, confirmed they received or saw the flyers and made multiple inquiries on the Muellers’ behalf after learning she might be alive.

“Because of those rumors, I will always hold on to that 1 percent possibility. That’s the whole reason we need her home,” Marsha Mueller told me, speaking by phone from Arizona. “It would be selfish on my part to want her to still be alive, imagining what she’s gone through, so I go back to this, that we want the truth, wherever that leads. I’m not afraid of finding out something, anything.”

Mueller and her husband maintain sporadic contact with the Hostage Recovery Fusion Cell, a multiagency task force monitoring Americans held hostage all over the world. The task force includes FBI agents, State Department diplomats, Pentagon officers, and others.

The Obama administration formed the Fusion Cell in 2015 in large part to monitor Americans held captive in Syria, but Mueller told me she found it “bureaucratic,” making it more difficult to connect with those directly involved in her daughter’s case. The last time she and her husband met with Fusion Cell officers, in January 2018, the couple was told there was “a preponderance of evidence that Kayla died,” but the officials provided nothing to support the vague conclusion.

“The intelligence community concluded in 2015 from information provided by Kayla’s ISIS captors that Kayla is deceased,” said Kieran Ramsey, director of the Hostage Recovery Fusion Cell, in an emailed statement in response to questions for this story. “The U.S. Government is committed to pursuing the terrorists responsible for Kayla’s captivity and death.”

Ramsey also said the case “is still considered an active investigation” and “we cannot provide additional information at this time.”

The Muellers over time have turned to sources in the region, including groups and individuals aiding the rescue of Iraqi Yazidi women and Syrian Christians. By necessity such sources are plugged into the dark world of ISIS trafficking and rely on trusted informants.

THERE ARE MORE THAN 8,000 documented cases of individuals abducted by ISIS whose whereabouts remain unknown, the Syrian Network for Human Rights said in a March report. They are mostly Iraqis and Syrians. As the battlefield contracted in 2019, it meant nearly all such abductees, if they are alive, are most likely within a geographic area controlled by the Kurdish-led Syrian Democratic Forces working with the United States in northeastern Syria.

Families of those abductees had hoped the battlefield defeat of ISIS would bring new information about loved ones. But ongoing turmoil and the failure of the U.S.-led international coalition to create any mechanism to account for ISIS captives prevent that.

Such work is left to human rights groups, a few NGOs, smugglers, and word of mouth—much of it now focused on ISIS “families” transferred to a displacement camp north of Baghuz.

The Al-Hol camp population has exploded, from just under 10,000 people in early December to more than 73,000 people by the end of May. Most are women and children in some way connected to ISIS.

‘It would be selfish on my part to want her to still be alive, imagining what she’s gone through.’—Marsha Mueller

Dozens of Yazidi women held by ISIS fighters, initially afraid to come forward, in recent weeks have been rescued from the camp and returned to Iraq. Two Christian women also have been retrieved and returned to their families.

I asked Kino Gabriel, spokesman for the Syrian Democratic Forces, about reports on Kayla Mueller. “I heard she was probably killed, and I also heard she was thought to be in Baghuz,” he said. “For almost all captured by ISIS we have received these kinds of different reports.”

Much of what the Muellers know of Kayla’s captivity they’ve gleaned through eyewitnesses—fellow Westerners now freed, three young Yazidi women held with Kayla, and at least one ISIS captor, Umm Sayyaf, the now-jailed wife of an ISIS leader.

Early on the jihadists held Kayla in a Raqqa prison in Syria along with about 23 other Westerners. The majority—including an Italian aid worker, four French journalists, and five European workers for Doctors Without Borders—were freed after paying large sums in ransom. Those from the United States, Britain, and New Zealand—countries with strict no-ransom policies—were killed or remain missing.

They include Americans James Foley, Steven Sotloff, Peter Kassig, and two British aid workers, all beheaded in 2014. British journalist John Cantlie, abducted with Foley, remains missing, and the British Home Office just months ago said it believes he is still alive.

The other missing hostage from the Raqqa prison is New Zealand nurse Louisa Akavi. A conflict veteran on her 17th mission into Syria for the International Red Cross, Akavi shared a cell with Kayla. The Red Cross made her abduction public in April this year.

Sightings of Akavi in an ISIS-controlled hospital and other areas have persisted. Like the Muellers, the Red Cross this spring canvassed northeastern Syria. As Al-Hol camp swelled with ISIS refugees, Swiss officers dispatched a Red Cross worker there to hoist its iconic flag in the middle of the camp, hoping Akavi might see it and be found.

Akavi and Kayla reportedly survived together some of the worst ISIS brutality, including torture, rape, and solitary confinement—much of it at the hands of Jihadi John and three British jihadists the hostages dubbed “the Beatles.” When Akavi became ill and suffered injuries, according to other hostages, Kayla stayed with her and demanded they not be separated.

Fellow hostages said Kayla remained strong though she was singled out for especially brutal treatment, in part because she was an American and because she openly refused to convert to Islam—all in the face of torment from Baghdadi.

In a letter smuggled out to Kayla’s parents, she wrote:

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 … I remember mom always telling me that all in all in the end the only one you really have is God. I have come to a place in this experience where, in every sense of the word, I have surrendered myself to our creator b/c literally there was no else. … + by God + by your prayers I have felt tenderly cradled in free fall. I have been shown in darkness, light + have learned that even in prison, one can be free. I am grateful …

Recounting what’s known about the captivity—and her faith in the midst of it—is important as questions persist, said Kathleen Day, who leads United Christian Ministry at Northern Arizona University, where Kayla attended. Day became friends with Kayla as her campus minister and has aided the Mueller family since.

Day said “people always had a claim on Kayla’s life,” and that didn’t change in captivity: “She was one person with no power, and she chose compassion, to stand with others. She lived her values and at the same time the most powerful country in the world left her behind.”

Umm Sayyaf, the wife of senior ISIS member Abu Sayyaf, is for now the last person to testify seeing Kayla alive. Captors moved Kayla to her home in the fall of 2014, where brutality continued in the company of three Yazidi teens enslaved to Sayyaf, the ISIS oil minister, and a Baghdadi confidant.

The Yazidis escaped, and the Muellers traveled to Germany to meet one of them. She told them Kayla inspired the teens’ flight but refused to accompany the Yazidis, fearing she would draw too much attention. In the Sayyaf home, the Yazidi said, the women were locked in rooms, chained, beaten, and deprived of food. Umm Sayyaf put makeup on them to “prepare” them for rape.

Kayla lived there until she left in a car driven by Baghdadi sometime in late 2014. In a 2015 raid, U.S. Delta Force soldiers captured Umm Sayyaf and killed her husband.

The Americans turned over Sayyaf—a 29-year-old Iraqi also known by the name Nisrine Assad Ibrahim—to Kurdish officials in Iraq. There U.S. officers interrogated her “many, many times” in 2015, said Karwan Zebari, director of policy and advocacy for the Kurdistan Regional Government office in Washington.

A counterterrorism court in Iraq tried Sayyaf in 2015 and sentenced her to life in prison. Last month, the Kurds allowed Sayyaf to speak publicly about her ISIS affiliation, which she stands by, and about Kayla in an interview with the British news outlet The Guardian. She claimed Mueller was “owned” by Baghdadi and said she “respected” the American. She said in 2015 she gave U.S. interrogators precise locations for safe houses used by Baghdadi in Mosul and elsewhere.

‘[Kayla] lived her values and at the same time the most powerful country in the world left her behind.’—Kathleen Day

The United States is under increasing pressure to extradite Sayyaf, and Zebari said he believed an extradition order had been prepared but not issued. Already in 2016 the FBI filed in U.S. district court in Virginia a criminal complaint against her, implicating her in the death of Kayla Mueller but providing no details.

At a meeting with the UN Security Council this spring, citing the “brutal conditions” Kayla and Yazidi women endured on Sayyaf’s watch, human rights lawyer Amal Clooney called for Sayyaf’s transfer to the United States to “face justice for those crimes.”

Others await justice too. Jihadi John was killed in 2015, but the three other “Beatles” are in custody—two in Iraq and one in Turkey, who already has been sentenced to 7½ years in prison for supporting a terrorist organization.

Baghdadi remains at large and remains the most wanted terrorist in the world. He appeared in an 18-minute video in May after terrorist attacks in Sri Lanka.

U.S. officials, who say a hunt is underway for Baghdadi, talk of reviving Guantanamo Bay as a detention center for ISIS war criminals. Bringing them to justice is likely to collide with U.S. policymakers who want to keep Islamic State militants out of the United States—and out of a 2020 election fray.

But pressure is building for a more coordinated international response to ISIS atrocities—and a full accounting of what happened to those caught in its clutches, like Kayla Mueller.

“What happened to Kayla was Baghdadi demonstrating what he was doing to America. He had the upper hand and he was raping America. It was retaliatory,” said Day. “What’s likely happened is she was killed in a coalition airstrike, and it’s being hidden from her parents. We all feel like we failed her. We listened to the government, and we did not do what should have been done. But there are 70,000 ISIS people in captivity now. Somebody knows.”