US:Likely Hostage Kayla Mueller Was Kept by ISIS Leader

U.S. intelligence agencies are investigating the possibility that the Islamic State militant leader killed Friday was the captor of American hostage Kayla Mueller for a time.

Adam Schiff, the ranking Democrat on the House intelligence committee, confirmed the connection at a breakfast with reporters Tuesday, but declined further comment. ABC News first reported that U.S. officials believe Mueller, whose death was announced in February, spent time in the custody of the Tunisian Islamic State finance man known as Abu Sayyaf.

A U.S. official on Tuesday said Sayyaf's real name was Fathi ben Awn ben Jildi Murad al-Tunisi.

Murad was killed Friday during a rare ground operation in Islamic State-held territory in Syria by Delta Force operators. His wife, known as Umm Sayyaf, was taken into custody and is being interrogated, U.S. officials say.

Murad had a number of aliases, the official said, but officials believe that Murad is his real name. Murad is believed to be the Islamic State's head of oil operations.

The official spoke on condition of anonymity because he was not authorized to discuss the matter publicly.

The Islamic State group said Mueller was killed in a Jordanian air strike, but U.S. officials have cast doubt on that assertion. Mueller and her Syrian boyfriend were taken hostage in August 2013 after leaving a Doctors Without Borders hospital in Aleppo, Syria. The boyfriend was later released.

White House spokeswoman Bernadette Meehan declined to address the issue.

"We are currently debriefing the detainee to obtain intelligence about ISIL operations," she said. "We are also working to determine any information she may have regarding hostages - including American citizens who were held by ISIL." 

A U.S. official also provided more details on the Friday night raid.

The commandos who flew by Black Hawk and V-22 Osprey aircraft into Syria under cover of darkness quickly met resistance on the ground. They blew a hole in the building where Murad was believed to be staying and as they ran into the building and up the stairs, they encountered more insurgents. The official said that at that point the U.S. forces battled in close quarters combat, including some hand-to-hand fighting.

The goal of the mission, which had undergone months of planning, was to take Murad and his wife alive, in the hopes that he would provide intelligence on the group's operations, finances and information on who they do business with and potentially on their leader, Abu Bakr al-Baghdadi. Another part of the plan was to free an 18-year-old girl who is a Yazidi and was believed to be kept as a slave by the Islamic State leader and his wife.

The girl was found and freed by the commandos and is expected to be returned to her family after she is debriefed by the U.S.

A team from U.S. intelligence agencies is poring over the laptops, cellphones, computer drives and other data recovered at the site.