Kayla Mueller's parents are still trying to figure out what exactly happened to their daughter who was held captive and killed by ISIS after Islamic State leader Abu bakr al-Baghdadi was killed in Syria in October."We're still not sure what happened to Kayla," Marsha Mueller, Kayla's mother, told Army Radio's Ilana Dayan. "Our government told us that ISIS killed her. ISIS told us that it was a bombing. That's why we're on this mission to find her and bring her home, so we can truly find out what happened to her. We really don't know." Kayla was an aid worker and activist who, according to US officials, had been repeatedly raped by al-Baghdadi himself before she died in Islamic State custody in 2015.Dayan asked Marsha why she wanted to know so much about Kayla's time in captivity."I need to be able to walk this horrific road with Kayla," said Marsha. "It's important to me to know every detail so that I can be a part of what happened to her – and I know now that she was writing and I continued on my side writing to her."When Marsha heard about Baghdadi's death, her "heart broke for the children that were killed with him." Kayla's father, Carl, told Dayan that they've been taking advantage of the situation to try and get more information about their daughter.At first, the United States government was unwilling to go into detail about what was happening until Sunday. President Donald Trump called them to inform them that the operation would be named after Kayla and spoke with Carl for about 18 minutes to answer questions.While Kayla was in captivity, she continued to hold on to hope that she would return home. "She let us know that she was still doing what she could inside to come home, and she was holding on to that hope up until the end," her mother said.Baghdadi, an Iraqi jihadist who rose from obscurity to declare himself "caliph" of all Muslims as the leader of Islamic State, died by detonating a suicide vest as he fled into a dead-end tunnel as elite U.S. special forces closed in on October 26.Marine Gen. Kenneth McKenzie, commander of U.S Central Command, which oversees American forces in the Middle East, said that Baghdadi brought two young children into the tunnel with him – not three, as had been the U.S. government estimate. Both children were believed to have been under the age of 12 and both were killed, he said.Reuters, Rachel Wolf and Ezra Taylor contributed to this report.