As security forces escalate crackdowns on Gülenist Terror Group (FETÖ) members, officials believe they still have about 5,000 adherents in the military's commands in Ankara.

FETÖ is accused of carrying out the brutal coup attempt on July 15, 2016 that killed 249 people. The terrorist group has benefited from its wide clout in the military where some among the top military brass turned out to be linked to the group after the coup attempt was quashed. Since the coup attempt, thousands of military officers have been detained or arrested and investigators have found that they managed to hide their ties to the group for decades while others were known Gülenists and were expected to be dismissed from the military before the coup attempt happened.

Investigators are now delving deeper into the secret FETÖ network in the military that avoided detection through various methods such as keeping contact with civilian FETÖ members at a minimum or entirely secret. As they unearth the network, particularly by tracing suspicious phone calls from military officers, investigators are identifying more infiltrators every day. Millions of phone calls, especially those made shortly before the coup attempt and in its aftermath, are the focus of the investigation. The group's secret "imams," or those coordinating members in the military, who have been detained had confessed to how they used landlines or phone booths to contact members without being detected. Investigators are also continuing to look into use of ByLock, an encrypted messaging app believed to be developed by the Gülenists, to identify the group's members. If this fails, they are also conducting extensive background checks to find if they had any links to companies or schools run by the terrorist group and their relations with known Gülenists. They also are delving into information about people's time at military schools. For decades FETÖ recruited young men and directed them to go to military school. Throughout their careers, those officers remained loyal to the Gülenists while disguising their ties. Investigations and confessions from former members have revealed that Fetullah Gülen, the group's fugitive leader, and "imams" instructed them to drink alcohol and marry women who do not wear headscarves to avoid detection. Before the coup attempt, FETÖ had disguised itself as a deeply religious group whose women wear headscarves and every member abstains from alcohol.