Ankara Chief prosecutor Yuksel Kocaman told reporters today that Gulen's movement is believed to have developed a program that makes innocent people appear to be using an encrypted messaging app which prosecutors say followers used to communicate secretly with each other.
Prosecutors considered the use of the app, Bylock, as evidence of membership in Gulen's network. Kocaman says Gulen's network developed the program to make it more difficult for authorities to trace real Bylock users.
Turkey blames Gulen for last year's failed coup attempt and has outlawed his movement. Gulen denies involvement. Turkey has arrested some 50,000 people since the coup and purged 110,000 others from government jobs.