In a new wave of operations against the Gülenist Terror Group (FETÖ) on Tuesday, authorities issued arrest warrants for dozens of suspects, mainly from the Turkish Armed Forces (TSK). Some 139 people, including active-duty soldiers, were arrested for links to the group which used its military infiltrators four years ago to stage a coup. The coup attempt was quelled, but it is estimated that the group’s members in the military managed to disguise themselves.

Prosecutors in the western province of Izmir, where the group’s fugitive leader Fetullah Gülen rose to prominence in the 1970s and ordered the arrests of 110 soldiers including five former officers. Eighty-nine suspects were arrested so far in the province and 24 other provinces. Arrest warrants stem from an investigation into a FETÖ network in the Turkish air forces and coast guard. Some suspects were identified through their contact with civilian FETÖ members acting as their "handlers" via payphones, a method commonly employed by the group to avoid drawing suspicion. Among wanted suspects were colonels, lieutenant colonels and officers of lower ranks. Also in Izmir, police re-arrested Fevzi Öztürk, an aide to the commander of TSK’s Aegean Army Command. Öztürk was released and placed on house arrest last month in a trial where he was charged with FETÖ membership. However, a new investigation disclosed his ties to the group’s infiltrators in the army.

In Istanbul, authorities ordered the arrest of 57 suspects in an investigation and 32 were arrested in operations in the city and 14 other provinces. Suspects included active-duty and retired military officers. They were identified in an investigation into a terrorist group’s scheme to plant its men in two military schools training cadets for the Turkish naval forces. Former FETÖ members arrested in earlier operations have given the names of suspects.

FETÖ is known for its devious tactics of widespread infiltration, everywhere from law enforcement to the army. Investigators have worked meticulously to uncover the methods FETÖ has employed. They are accused of running such a scheme in the navy’s schools, giving each applicant to the schools a special application code that would help FETÖ-linked officers interviewing the applicants to identify which would-be cadets were linked to the group. Thus, others without code numbers supplied by the group would be eliminated by interviewers while those loyal to the group would avoid suspicion. In an earlier investigation, authorities have discovered that between 2004 and 2016, FETÖ assigned "applicant numbers" for its infiltrators in the Turkish air force as well, for use in admission to military school.

Police arrested 17 suspects in another operation that came after arrest warrants were issued by the Chief Prosecutor’s Office in the capital Ankara. They were among 25 wanted suspects. All are accused of being part of the terrorist group’s secret network in the Turkish air forces. Police launched operations in Ankara and other provinces to capture the suspects at large. Authorities said suspects were four former noncommissioned officers and civilians who served as "secret imams," a name given to FETÖ handlers for military infiltrators. Their identities were discovered based upon the testimonies of suspects captured in earlier operations who invoked a remorse law. Remorse law allows suspects to be handed down a much more lenient sentence in exchange for collaboration with authorities. Security sources said "secret imams" were in charge of small cells of military personnel and tracked activities of infiltrators starting from their graduation from the military academy. Military infiltrators would be "handed over" to different handlers when they were reassigned to different provinces during their military careers. Investigators say infiltrators were required to attend "regular meetings" with their handlers and asked to supply their information to the terrorist group about their superiors and subordinates.

In the southwestern province of Muğla, prosecutors ordered the arrest of seven officers, including two who were dismissed from the army on the suspicion of having links to the terrorist group.

FETÖ’s military infiltrators tried to topple the government on July 15, 2016, and killed 251 people in the process while injuring nearly 2,200 others. The group faced heightened scrutiny after the putschist bid, and thousands of people linked to them were detained or arrested since the summer of 2016.