The Ankara Public Prosecutor's Office, in cooperation with the Defense Ministry, is investigating thousands of officers and civil personnel within the Turkish Armed Forces (TSK) for possible links to the Gülenists Terror Group (FETÖ). The special investigation does not cover the some 9,000 officers already discharged from the military for direct involvement in last year's deadly coup attempt on July 15.

According to a report in the HaberTürk daily, the investigation has been ongoing since the coup attempt and is aimed at catching FETÖ operatives whose true identities remain hidden. Most of those under investigation are involved in passive duties.

The probe is uncovering decades-long attempts by FETÖ to infiltrate the military, with investigators even analyzing suspects' military academy admissions test results. It was shown that one suspect who failed the admissions test had proceeded to enroll and was eventually promoted to major. The same suspect was found to have installed the ByLock messaging app on his phone, which is almost exclusively used by FETÖ members.

Investigators are focusing on students who answered all the questions on the test correctly. It is known that FETÖ used its operatives at various state institutions to get a hold of such tests before distributing them to its own junior members to infiltrate various agencies, including the judiciary, military and police.

It was noted that the English proficiency tests held in December 2010, April 2012 and September 2014 saw an abundance of applicants answer more than 90 percent of the questions correctly, obliging investigators to focus on those students. Some students who received over 90 points out of 100 questions were later interviewed by officials and were later arrested for suspected membership in FETÖ.

Suspected officers who received master's or doctoral degrees from known FETÖ members in academia are also under investigation, and as of, now 40 detailed administrative investigations have been launched.

The investigation into any lingering FETÖ presence in the military is also focusing on FETÖ's modus operandi. It is known that FETÖ coerced its up-and-coming members to marry within the group. That is why all marriages of suspects are also being examined. One couple, both majors, is known to have fled to the U.K. after last year's coup attempt. It was shown that both the correct and false answers of the couple were the same on the English proficiency test they took several years ago.

FETÖ was also very influential in the annual Supreme Military Board (YAŞ) meetings in 2011, 2012 and 2013, in which promotions and dismissals within the military are decided. Only two of the dozens of officers promoted to general in these years did not participate in the July 15 coup attempt. In 2015, with many of FETÖ's criminal activities having come to light, the group forced those of its members who were known to authorities into retirement while promoting those who remained hidden to general.