According to the source, speaking on condition of anonymity due to restrictions on talking to the media, a total of 39 people were detained last month during a FETO probe of sleeper cells that have infiltrated critical offices in Turkey. 

Four of the remanded suspects, including deputy governors, are charged with forming a terror organization, while the remaining 16 are accused of belonging to an armed terrorist organization, the sources said. 

The court released 19 others but ordered that they remain in Turkey, the sources added. 

The July 15 coup attempt resulted in the deaths of over 240 people and injured more than 2,100, leading to a nationwide probe to eliminate FETO sleeper cells that had infiltrated state institutions, including the judiciary and army.

Fetullah Gulen, who the Turkish government says heads the Fetullah Terror Organization, has been living in Pennsylvania since 1999.