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.”