The authorities' probe into ByLock, an encrypted messaging app almost exclusively used by the Gülentist Terror Group (FETÖ), revealed that police intelligence staff linked to the terrorist group were behind the app used to relay the group leader's messages to followers.

A wave of arrests after last year's July 15 coup bid targeted people using ByLock, an encrypted messaging app. The latest findings demonstrated that the FETÖ-linked staff working in a powerful intelligence department of the Turkish National Police were the "architects" of the app, or rather its modification to serve the purposes of the group. A group of intelligence officers are accused of controlling the secretive app used to deliver the messages of FETÖ leader Fetullah Gülen to his followers, as well as to instruct the group's members on how to carry out plots against anti-Gülenists. The terrorist group is implicated in orchestrating the coup attempt last year that killed 250 people.

The investigations show that 95 out of the first 100 people who downloaded and installed the app were personnel of police intelligence and the other five people were employees of the Scientific and Technological Research Council of Turkey (TÜBİTAK). TÜBİTAK was the target of mass infiltration by Gülenists in the past, and it is believed that developers of the application are linked to this state-run institution.

The usage of encrypted messaging apps by the terrorist group fell in the spotlight after last year's coup attempt. An investigation launched in early 2016, months before the coup attempt, discovered that the ByLock app was exclusively used by FETÖ for correspondence, with shared topics ranging from coup plans to Gülen's statements.

The ByLock investigation was expanded after the coup attempt and thousands of people accused of using the messaging app for communicating Gülen's messages to subordinates and for pro-terrorism propaganda have been detained or arrested.