"PRESCOTT, Ariz. - The brother of an American woman who was killed after spending months as a hostage of the Islamic State of Iraq and Syria (ISIS) 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."

Mueller's death was confirmed Feb. 10 by her family and U.S. officials. ISIS 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."

Bowe Bergdahl swap killed deal for Kayla Mueller, brether says - CBS News

"The young woman'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."

"I actually asked the president that question when we were in the White House," Carl Mueller said without elaborating."