Police detained 33 suspects yesterday in nationwide operations as part of an investigation into ByLock, an encrypted messaging app exclusively used and developed by members of the Gülenist Terror Group (FETÖ).

Istanbul's Chief Prosecutor's Office had issued detention warrants for 38 suspects, and the manhunt was underway to capture the remainder of the suspects when Daily Sabah went to print. The suspects are charged with "membership of a terrorist group."

The detentions follow the interception of messages exchanged by suspects on ByLock. The identities of the suspects were not disclosed, but media outlets reported that they included former police officers, teachers, dentists and a tax inspector. Police seized the computers and cellphones of the suspects, checking for more digital evidence linking them to FETÖ.

Though an investigation is already underway, ByLock was first heard of publicly after 2016's bloody coup attempt blamed on FETÖ's infiltrators in the military.

Investigators have managed to decode millions of messages sent and received by Gülenists; however, more messages are still being decoded.

ByLock was discovered during criminal inquiries into the terrorist group, whose criminal activities have been in the spotlight since its two coup attempts in 2013. The National Intelligence Organization (MİT) uncovered the messaging app apparently programmed - or modified for exclusive use for the group's members - through someone linked to FETÖ. According to recent media reports, police intelligence staff linked to the terrorist group were behind the app. 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 private app used to deliver FETÖ leader Fetullah Gülen's messages to his followers, as well as to instruct the group's members on how to carry out plots against anti-Gülenists.

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.