As part of the investigation launched into the Gülenist Terror Group (FETÖ), 16 suspects were detained during simultaneous operations launched into the group's network in 11 different provinces.

The operations, based in the western province of Bursa, were launched by the Bursa Public Prosecutor's Office. Counterterrorism units of the Bursa Provincial Police Department revealed that all suspects had used the network's encrypted messaging application, ByLock.

Testimony from Gülenists in the bureaucracy, detained after the July 15 putsch attempt, pointed to the prevalence of app use. Prosecutors say ByLock was popular among Gülenists for secretive communications between 2013 and 2015, and after 2015, the terror cult turned to Eagle IM, which offers "256-bit end-to-end AES encryption" to its users, according to the app's description in the Google Play Store. The app's developers also promise protection from "man-in-the-middle" attacks that consist of hacking into private two-way chats, enabling a third-party to alter messages. Similarly, ByLock was offering an eight-digit password for users and highly secure encryption.Various ministries have since launched an investigation into workers who allegedly used ByLock by actively suspending and terminating app users who were found to be active members of FETÖ. The failed July 15 coup attempt, which left 241 people dead and nearly 2,200 injured, was allegedly organized by followers of Fetullah Gülen, who has lived in self-imposed exile in the United States since 1999. Gülen has led a long-running campaign to overthrow the state through infiltration of state institutions, particularly the military, police and judiciary.