Workers Party (İP) Chairman Doğu Perinçek, İP Secretary-General Ferit İlsever and Cumhuriyet daily chief columnist İlhan Selçuk, as well as a former İstanbul University rector, Kemal Alemdaroğlu were detained as part of an investigation into a criminal network that calls itself Ergenekon, after a legend of how Turks came into being.
The ongoing investigation had previously uncovered evidence showing that the gang was attempting to prepare the ground for a coup d'état in Turkey in 2009. Ergenekon is suspected of shady links to groups hidden within the state. These groups are commonly referred to as Turkey's "deep state," a vague concept of a phenomenon in which individuals and groups occupying various positions in the state take justice into their own hands to shape Turkey in accordance with their political convictions.
The arrests come at a time when allegations have been made that a recent closure case against the ruling Justice and Development Party (AK Party) was filed with the Constitutional Court to prevent further development of the Ergenekon investigation.
The police have also raided the offices of TV station Ulusal Kanal (National Channel) and the Aydınlık newsweekly.
The arrests follow the interrogation on Wednesday of Sedat Peker -- an ultranationalist underworld leader currently serving 14 years in prison for involvement in organized crime -- over his alleged links to the Ergenekon gang. Suspects of the 1996 Susurluk affair Yaşar Öz and Semih Tufan Gülaltay were also interrogated by the prosecutor on Wednesday as part of the same investigation.
In January 39 suspects were arrested during raids targeting the gang, including retired Gen. Veli Küçük, nationalist lawyer Kemal Kerinçsiz, academic Emin Gürses and press speaker of the so-called "Turkish Orthodox Patriarchate."