One senior Turkish official said Turkey has captured the sister of dead ISIL leader Abu Bakr al-Baghdadi on Monday in the northern Syrian town of Azaz, reported several media outlets.

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Rasmiya Awad, 65, was detained in a raid near Azaz, the official said, referring to a Turkish-controlled Syrian town near the border. When captured, she was accompanied by five children. Her husband and daughter-in-law who were also detained are now under interrogation.

"We hope to gather a trove of intelligence from Baghdadi's sister on the inner workings of ISIS (ISIL)," the official told Reuters.

Al-Baghdadi killed himself, along with his three children last month, after getting trapped in a dead-end tunnel in northwestern Syria by U.S. special forces. ISIL, in an audio tape posted online on Thursday, confirmed that its leader had died and vowed revenge against the United States.