Four of the nine suspects with links to the Gülenist Terror Organization (FETÖ) detained in counterterrorism operations in western Turkey’s Denizli province were arrested on Monday.

The suspects were captured in eight simultaneous operations carried out by the counterterrorism branch of the provincial security directorate in the city center. The operations were conducted within the scope of a probe launched by the Chief Public Prosecutor’s office in Denizli.

Police seized organizational documents and digital materials in raids on the suspects’ properties. Investigations revealed that the suspects contacted the members of the terrorist organization via public telephones. Three former soldiers and a former military school student were later arrested by the court while the other five suspects were released on condition of judicial control.

FETÖ planted its members throughout state institutions, from the police to the judiciary, army and bureaucracy, over the course of many years, according to prosecutors. Followers managed to rise to high ranks within the state while hiding their links to the group, becoming army generals and senior police chiefs. Through its so-called "imams," FETÖ backed infiltrators and gave covert orders.

The terrorist group was behind the July 15, 2016 coup attempt that killed 251 people and injured nearly 2,200 others. Tens of thousands of people were detained or arrested following the coup attempt, and a barrage of trials was launched against FETÖ, both for its role in the attempt and other crimes.