Several Yazidi girls who were imprisoned by Islamic State militants spoke to the BBC recently about American aid worker Kayla Mueller's time in captivity.
One of the girls, who gave her name only as Amshe, claims that the Islamic State was responsible for Mueller's death, based on a conversation she had with Haji Mutazz, the group's second-in-command. Mutazz was holding Amshe as a sex slave.
The Islamic State, also known as ISIS had previously claimed that Mueller was killed in an airstrike by the U.S.-led coalition against the militant group.
Mueller was an American aid worker who began working on the Syria-Turkey border in 2012. ISIS captured her in Syria in August 2013.
The BBC interview, published Thursday, focuses on accounts by Dalal and Susan, two young Yazidi girls who escaped from Islamic State captivity and have since returned to northern Iraq. The girls say they met Mueller when all three shared a prison cell. Their recollections reveal previously unknown details about Mueller's time as an ISIS prisoner.
U.S. officials told Mueller's parents in June that the group's leader, Abu Bakr al Baghdadi, raped Mueller "repeatedly" while she was in captivity. Dalal and Susan confirmed this to the BBC.
The two girls said Mueller told them that after she was kidnapped, her fingernails were pulled out in an effort to torture her into confessing that she was a spy.
Mueller used notebooks to write of her travels in India and France, and kept busy by reading books. She had learned some Arabic from Islamic State members, according to Susan.
The girls also recounted how caring Mueller was. "When IS brought food for us, Kayla ate very little," Susan said. "She didn't want us to be hungry."
Mueller shared stories about her life in the U.S., while the other two told her of their own lives back home.
When Baghdadi would call for Mueller to pay him a visit, Dalal said she would come back "shaken," according to the BBC. He allegedly told Mueller that he would behead her unless she married him. Baghdadi subsequently married her and raped her, Dalal explained, though he never referred to her as his slave, the way he did with a Yazidi girl he also raped.
Baghdadi paid extra attention to Kayla, the girls said, and gave her a Quran and a wristwatch as gifts. He dressed her in all black and banned other men in the house from looking at her.
But other men took interest in Kayla, too, Amshe said. Mutazz made Mueller his sex slave as well, viewing her as a trophy because of her American nationality.
That's also the reason Islamic State leadership ultimately killed Mueller: Amshe says Mutazz told her it was an effort to seek revenge on the West.