Turkey captured the sister of slain Islamic State leader Abu Bakr al-Baghdadi on Monday in the northern Syrian town of Azaz, a senior Turkish official told Reuters, and is interrogating her and her husband and daughter-in-law who were also detained.

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 also accompanied by five children.

“We hope to gather a trove of intelligence from Baghdadi’s sister on the inner workings of ISIS,” the official said.

Little independent information is available on Baghdadi’s sister and Reuters was not immediately able to verify if the captured individual was her.

Baghdadi killed himself last month when cornered in a tunnel during a raid by US special forces in northwestern Syria.

Islamic State, in an audio tape posted online on Thursday, confirmed that its leader had died and vowed revenge against the United States.

The group, also known as ISIS, said a successor to Baghdadi identified as Abu Ibrahim al-Hashemi al-Quraishi had been appointed.

A senior US official last week said Washington was looking at the new leader to determine where he came from.