Turkish intelligence was aware of an ISIS operative, Mohammed Khlef Ibrahim Ibrahim, surveilling Christian and Jewish sites in Turkey but failed to notify law enforcement to prevent a potential attack.

Documents obtained by 'Nordic Monitor' reveal that Ibrahim, alias "Abu Leys," operated as part of a sleeper cell in Balıkesir, having gained Turkish identity documents that allowed him to move freely and set up a business.

Ibrahim traveled across Turkey, meeting with other ISIS members while remaining undeterred by the risks of detection, including using bus travel that was monitored by authorities. In late November 2023, he and accomplice Mijbel al-Shuwaikhi conducted reconnaissance in Istanbul.