Police detained a total of 83 personnel during an operation at the Palace of Justice in Istanbul's Çağlayan district, along with the Gaziosmanpaşa and Büyükçekmece district courthouses early on Friday.

The personnel were detained upon the order of the Istanbul chief public prosecutor's office as part of the ongoing Gülenist terror cult (FETÖ) investigation.

The operation spread to 24 other provinces because some of the suspects were inducted to other provinces after working at the inspected courthouses in Istanbul.

The suspects are accused of acting in accordance with the Gülenist terror cult, the main suspect behind the failed July 15 coup, as well as using Bylock, an encrypted messaging app allegedly used by FETÖ members to avoid detection.

The suspects are also accused of financing FETÖ and cheating in public exams for taking official posts.

On July 15, a group of rogue soldiers associated with FETÖ, led by Fetullah Gülen, - who lives in self-imposed exile in the U.S. - attempted to overthrow the democratically elected government in Turkey through a military takeover, killing over 240 people and injuring over 2,000.

Gülen and his followers are accused of attempting to infiltrate Turkey's state institutions -- especially the military, police apparatus and judiciary -- with the ultimate aim of creating a parallel state. Turkey has requested the extradition of Gülen from the U.S. to stand trial for a series of crimes.