Orhan Sipahioğlu, who was previously claimed to be a top member of the Gülenist Terror Group (FETÖ) and pointed out as the one responsible for cult member military officials in the Turkish Naval Forces, was taken into custody in Istanbul on Monday.The police conducted a detailed search at Sipahioğlu's residence and seized hardcopy and digital documents belonging to the suspect. It has also been reported that police will ask writer Nurettin Veren to testify since he accused Sipahioğlu of being the most important FETÖ member in the Naval Forces on a live TV program.Sipahioğlu, who was previously a major in the Naval Forces, was discharged from the military in 1994. Following his discharge, he began working at the Istanbul Metropolitan Municipality and became deputy mayor of the Gebze Municipality in 2011. He retired from his duties in Gebze in September last year.