The Obama administration’s swap of five Taliban leaders held at Guantanamo Bay for accused Army deserter Bowe Bergdahl may have doomed any hope Kayla Mueller’s family had for working out a deal with ISIS, the murdered aid worker’s family said in an interview.

Carl Mueller told NBC in an interview that aired Monday that he and his wife thought they could win his daughter’s freedom with a $6.2 million ransom payment, although he acknowledged the Arizona family faced a daunting task in raising that much money. But when the White House agreed last year to trade Bergdahl, who had been held for five years by the Taliban and Haqqani network, the family believes the price for their daughter went up.

"They realized that, ‘Well, if they're gonna let five people go for one person, why won't they do this?'"

- Eric Mueller, brother of Kayla Mueller

“That made the whole situation worse,” Kayla Mueller’s brother, Eric, told the network. “Because that's when the demands got greater. They got larger. They realized that they had something. They realized that, ‘Well, if they're gonna let five people go for one person, why won't they do this? Or why won't they do that?’”

Islamic State announced earlier this month that Mueller, who was taken hostage Aug. 4, 2013, had been killed by a Jordanian airstrike that was conducted as retaliation for the terror group’s savage murder of a Jordanian air force pilot. The Islamist group later provided the Muellers with undisclosed evidence that she was indeed dead.

Mueller, of Prescott, Ariz., had volunteered with aid groups in India, Israel and the Palestinian territories before going to Turkey to work with Syrian refugees. Her identity was not disclosed until the terror group claimed she was dead, because the family was still hoping to win her release.

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“We understand the policy about not paying ransom,” he told NBC. “But on the other hand, any parents out there would understand that you would want anything and everything done to bring your child home. And we tried. And we asked. But they put policy in front of American citizens’ lives.”

Still, the family worked to meet the terrorist group’s demands. And when the Bergdahl trade was announced, the Muellers thought it could mean the government might consider a similar deal for Kayla.

Bergdahl was freed May 31, 2014, in exchange for key Taliban leaders. The deal has been heavily criticized, in part because the Taliban leaders were predicted to go back to the battlefield, and also because the circumstances of Bergdahl’s capture are still unclear. Many of the soldiers who served with him say he deserted, and the results of an Army investigation into the matter, which could result in a court-martial of Bergdahl if he is found to have deserted, have not been released.

“If they're gonna let five people go for one person, why won't they do this? Or why won't they do that?’” Carl Mueller said he thought at the time.

“I actually asked the president that question when we were in the White House," he said. "Yeah, that was pretty hard to take.”

In the end, U.S. adherence to the policy of not negotiating with terrorists – at least in the case of Kayla Mueller – may have marked her for death.