PHOENIX — Kayla Mueller was in a detention cell in Syria, face to face with her boyfriend who was posing as her husband. Had she told her captors she was married to Omar Alkhani, she might have been freed from the hands of Islamic State militants, he said. Instead, she denied being his wife.

Alkhani had persuaded a string of people to let him plead for her release, but he left empty-handed. He said he saw Mueller’s face for just a few seconds when guards uncovered it to show it was the American hostage from Prescott, Arizona.

The guards told Mueller, 26, that Alkhani would not be harmed if she told the truth, so she apparently stuck to honesty to save him rather than take the slim chance to save herself, he said.

“Since she’s American, they would not let her go anyway. No sense to stay here, both of us,” Alkhani said. “Maybe she wanted to save me. Maybe she didn’t know I came back to save her.”

Thinking about others first was Mueller’s nature. She had long been content without spending the wages she earned as an international aid worker on new clothes, a hair dryer or makeup so she could use her money to help others instead, Alkhani said.