Three people were arrested Tuesday over the alleged use of a new messaging app linked to the Gülenist Terror Group (FETÖ).

The Ankara Western Chief Public Prosecutor's Office launched an investigation in March after a former police officer, named Cumali K., who was expelled from his post over FETÖ links, was contacted again by members of the organization.

According to a judiciary source, who asked not to be named due to restrictions on speaking to the media, the former police officer confessed that three FETÖ members he had worked with visited him and asked if he needed any material or moral support.

He said the FETÖ members installed a program called Cryptnote on his phone and computer, calling it "more reliable" than ByLock, another suspected means of communication for the group.

Under the direction of prosecutors, Ankara police tracked the three FETÖ members, İdris D., Mahmut O. and Mutlu D., and found they were allegedly visiting people associated with the group and took them into custody.

After questioning at the prosecutors' office, the suspects were arrested on charges of being members of a terrorist organization.

The suspects were allegedly working on restructuring FETÖ by uploading the encrypted Cryptnote messaging app on the computers and phones of FETÖ members who were expelled from the civil service.

The investigation also found the suspects were allegedly in contact with the families of arrested FETÖ members to prevent them from exposing the group.

They also allegedly acted to hinder members' confessions and keep up the morale of the non-exposed members.

The usage of encrypted messaging apps by the terrorist group fell under the spotlight after last year's coup attempt blamed on FETÖ's infiltrators in the army.

An investigation by authorities launched in early 2016 discovered that the ByLock app was exclusively used by FETÖ for correspondence, the topics of which ranged from coup plans to sharing 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.