The American and British hostages who were barbarically beheaded by ISIS last summer were held at the same location in northern Syria for more than four months and were not moved around as often as previously thought, U.S. and British security sources said, raising questions about the thoroughness of Western military and intelligence efforts to find them and whether more could have been done to save the captives.

And in an interview with The Daily Beast, the boyfriend of Kayla Mueller, Omar Alkhani, said that he was in a desperate race to win her release. Both his efforts and those of the Americans, however, ultimately failed.

In an effort to conceal their location, ISIS moved its American and British captives among different makeshift prisons in 2013. But from late February 2014 until July of that year, the hostages were gathered in one compound in Raqqa, ISIS’ de facto capital, having been moved there as fighting between rebel groups plunged insurgent-held areas in northern Syria into chaos. By the time a U.S. military rescue operation was launched on July 4, ISIS had moved its hostages, perhaps only a day or two earlier.

“This wasn’t a failed rescue mission,” said a British security source. “This was a rescue mission that was far too late.”

U.S. officials have insisted that they launched a rescue mission as soon as they were confident in intelligence that showed where ISIS was holding the hostages. But the news that their loved one had been in the same location for so long will add to the dismay of the captives’ families, some of whom have criticized the administration for not doing more to snatch the captives from the militants.

The Daily Beast reported last week that by the end of the first week of June, the British government had given the Obama administration what it believed to be precise intelligence about the location of four American captives. However, U.S. and British officials said the White House waited a month to launch a rescue mission because of concerns that the intelligence wasn’t conclusive and because they didn’t want to order an operation based on information provided by a foreign service.

ISIS eventually killed its three male American captives, and the only woman in the group’s custody died under circumstances that still haven’t been fully explained. The group is still holding a British journalist, John Cantlie.

According to a timeline provided by security sources, who spoke to The Daily Beast on the condition of anonymity, most of the terror group’s Western hostages were moved from the basement prison of an Aleppo children’s hospital to the city’s industrial zone in late August 2013. Then, just before Christmas Day, they were moved again, this time northwest of Aleppo. When infighting broke out between insurgents in early January 2014, they were relocated yet again in what the sources described as a “panic move” to Idlib province, southwest of Aleppo.

During January there were several more moves through “transit locations” that took the hostages further east into the ISIS stronghold of Raqqa, sources said. But in February, they were gathered in one compound southeast of the city in an oil storage facility and remained there until just days before the rescue mission by U.S. Special Forces.

British officials, as well as private security contractors, say they were frustrated by Washington’s hesitance to give the go-ahead for the rescue attempt. The following month, in August, ISIS began beheading its American and British prisoners in a series of grisly Internet videos. President Obama himself conceded in an interview with BuzzFeed News last week that they “probably missed [the hostages] by a day or two.” But he said it wasn’t fair “to say that the United States government hasn’t done everything we could.”

Top Obama administration officials insist there was no delay and that when they had “matured” the intelligence and confirmed it with their own debriefings of European captives who had been released they quickly gave the green light for the rescue bid. Speaking to the Washington Post, Susan E. Rice, Obama’s national security adviser, said that when the president was presented with a final operational plan to rescue American journalists James Foley and Steve Sotloff and aid workers Peter Kassig and Kayla Mueller the deliberations “began on a Friday and ended on a Saturday evening,” when the president gave his approval.

Among the criticisms from private security contractors and European officials about how the Obama administration handled the search for the hostages is its placing a higher priority on surveillance and electronic intelligence while downplaying the importance of human intelligence.

One of those moved by ISIS between November 2013 and the following January, before the American hostages were settled outside Raqqa, was freelance photojournalist Omar Alkhani, who has worked for Reuters and spent years documenting the suffering of Syrian civilians. He and Mueller, who was then his girlfriend, were taken hostage on August 4, 2013, after leaving a Doctors Without Borders hospital near Aleppo.

In an interview on Sunday with The Daily Beast, Alkhani added new details to Mueller’s personal story and her experience as an ISIS prisoner. The pair first met in Cairo in the summer of 2010, and struck up a relationship largely via Facebook messages, Skype calls, and emails. They shared a desire to help the Syrian people, ravaged by years of civil war and suffering under the strongman Bashar al Assad.

The pair would see each other during trips in the region, and eventually took an apartment together in Turkey in 2012. Mueller began work with an aid group, Support to Life, helping Syrian refugees.

Alkhani described the 26-year-old aid worker as an almost impossible idealist, who gave away the money in her pockets to poor people on the street and refused to buy clothing and makeup for herself. One morning, Alkhani recalled waking up to find that Mueller had cut her hair using a kitchen knife.

“I said, ‘Why are you doing this? You can go to the salon and get a nice haircut.’”

“She said, ‘I don’t want to spend money on something I can do myself.’”

Alkhani said that Mueller grew tired of working in an office and was eager to go into Syria to see the plight of the people up close, and perhaps to write about the experience on her personal blog. A friend of Alkhani called and asked him to make a trip to a Doctors Without Borders hospital outside Aleppo, to help restore Internet service. Alkhani wasn’t a technical engineer, but he had enough experience with the type of equipment the hospital used that he knew how to make the repair.

Mueller said she wanted to come, too. Alkhani resisted, saying Syria was too dangerous for an American. But he eventually agreed to Mueller’s request, because he feared she would find some way into Syria without him, and that he wouldn’t be able to protect her.

The pair were supposed to be in Aleppo only for a day or so and invented a cover story in the event they were detained: Alkhani would say Mueller was his wife, believing that no one would harm her if they were married. Contrary to a previous statement from Doctors Without Borders that hospital officials were surprised and worried to see Alkhani had brought an American companion into Syria, he told The Daily Beast that he’d phoned ahead and spoken to a hospital employee, who said it was safe to bring Mueller.

The pair stayed overnight at the hospital and left the next morning in a car with one other passenger and a driver, headed for a bus station where they would begin their trip back to Turkey, Alkhani said. Only a few minutes into the journey, however, their car was pulled over by a larger vehicle carrying at least half a dozen armed men. They didn’t immediately identify themselves as ISIS, Alkhani said, but they took the group to a jail, which he later learned was the children’s hospital basement in Aleppo.

Mueller was shaking with fear, he said, but he assured her that they would be safe, and that the men would let them go once they realized the pair had come to Syria on a humanitarian mission. But for the next month, Alkhani was beaten and tortured by his ISIS captors, who accused him working for the “kaffir,” or non-believers, at the hospital. Apparently suspecting him of spying, they also inspected his camera and wanted to know why he was installing computer equipment at the hospital.

Mueller was kept in a separate room in the jail, Alkhani said, but she communicated to him by coughing when he was nearby. On Sept. 2, 2013, Alkhani was freed, and he said he immediately set to work trying to hatch a plan to rescue Mueller. He called her parents in Arizona, who by then had already been informed that she’d been taken prisoner, according to a family representative.

Alkhani said that through a friend, whom he didn’t identity, he was able to make contact with a senior ISIS official, whom he described as a “judge.” In late November 2013, Alkhani ventured into Syria once again and told the judge that Mueller was his wife—their cover story all along. To Alkhani’s surprise, however, the judge said that Mueller had said she wasn’t married.

The judge allowed Alkhani to speak to Kayla in person. “I saw Kayla, and I asked her, ‘Why are you telling them you’re not my wife?’” Alkhani said. He said she began to cry and replied, “I don’t know.”

The judge told Mueller that if she told the truth about Alkhani, he wouldn’t be harmed. Mueller replied that Alkhani was her fiance, and that they had agreed to marry. Alkhani said he tried to impress upon Mueller that this was her only chance to leave the prison, but that she began to cry harder, and that he was no longer able to hear what she was saying. At that point, guards took him from the room. He said he was kept in ISIS custody for another two months, and that his captors moved him twice. But while he could overhear guards talking about two other American prisoners, Foley and Sotloff, he said he didn’t see Mueller again. He also never heard anyone mention Kassig, the fourth American hostage.

Alkhani said he had no explanation for why Mueller didn’t go along with their cover story. But he emphasized that she had come to Syria only to help the people and alleviate human suffering.

Indeed, before the pair lived together in Turkey, Alkhani said Mueller had tried to send him surveillance cameras and microphones, so that he could document the atrocities of the Assad regime in the suburbs of Damascus. But it was too difficult to send packages into Syria, and Mueller’s attempts to get the equipment in via Jordan and Lebanon also failed, he said.

“But she supported us,” he said. “She used to say, ‘I want to use my freedom to help you get your freedom.’”