PRESCOTT, Ariz. — The brother of an American woman who was killed after spending months as a hostage of Islamic State militants says Kayla Mueller’s situation worsened after the government traded five Taliban commanders for a captive U.S. soldier. The militants increased their demands after the May swap for Army Sgt. Bowe Bergdahl, Eric Mueller told NBC’s “Today” in an interview that aired Monday.

“That made the whole situation worse because that’s when the demands got greater,” he said. “They got larger. They realized that they had something.”

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Eric Mueller talks about his sister, Kayla Mueller, during a candlelight memorial in Prescott, Ariz., last week. Mueller’s family says the government valued policy more than their family.

Mueller’s death was confirmed Feb. 10 by her family and U.S. officials. The Islamic State group claimed she died in a Jordanian airstrike, but U.S. officials have not confirmed that. The Pentagon said it didn’t know how she was killed.

The 26-year-old international aid worker, who grew up in Prescott, Arizona, was captured in August 2013.

Mueller’s father, Carl Mueller, said that the United States’ willingness to swap for Bergdahl but not pay ransom or allow ransom to be paid for his daughter “was pretty hard to take.”

Mueller’s parents said the U.S. government put policy ahead of American lives.

White House spokesman Josh Earnest said Monday that the Mueller family had been put in a difficult position by the U.S. policy against making concessions to terrorists, but he defended it as being in the best interests of the nation.