Before her death earlier this year, American hostage Kayla Mueller was repeatedly raped by ISIS leader Abu Bakr Al-Baghdadi, according to U.S. intelligence officials.

Mueller's family confirmed to ABC News that government officials have told them that their daughter, who would have turned 27 on Friday, was the victim of repeated sexual assaults by al-Baghdadi.

"We were told Kayla was tortured, that she was the property of al-Baghdadi. We were told that in June by the government," said Kayla's parents, Carl and Marsha Mueller, who spoke exclusively to ABC News today.

Mueller, whose death as the result of a Jordanian airstrike, was reported in Feburary, was kidnapped in Syria with her boyfriend in August 2013 while leaving Spanish Médecins Sans Frontières (Doctors Without Borders) hospital in Aleppo. ISIS demanded $5.5 million for her release, according to The Independent.

Mueller was held for a time by Islamic State financier Abu Sayyaf and his wife Umm Sayyaf. Al-Baghdadi. During her captivity, as reported by a Yazidi (religious sect) girl who escaped, Mueller was taken by Al-Baghdadi as his wife and repeatedly raped when he visited. Rape was allegedly a "reward" for ISIS victories, and many women reportedly passed through the Sayyaf house on their way to being given as "presents" or sold to ISIS militants.

The Yazidi girls say the sex trade was organized by Umm Sayyaf, who was captured in Syria in May by U.S. Special Forces. Abu Sayyaf was killed a month later in June during a Delta Force raid which resulted in a treasure trove of intelligence about ISIS being uncovered, according to NBC's Idaho affiliate KHQ 6.

Last week, the U.S. announced that Umm Sayyaf was handed over to Kurdish authorities in Irbil to be put on trial. However, many U.S. prosecutors had hoped to try her in federal court in Manhattan.