A high-ranking suspect acting as the so-called "imam" of Turkey for the Gülenist Terror Group (FETÖ) was detained in a raid Istanbul, reports said Wednesday.

Following coordinated efforts by the counter-terrorism directorate of the Istanbul Police Department and the provincial office of the National Intelligence Organization (MİT) to reveal the hideouts of the shadowy group, a safe house in Istanbul's Kartal district was raided by police and intelligence officers on Tuesday.

The suspect identified only by his initials as M.Y., his wife G.Y. and daughter B.Y. were detained in the raid. G.Y. was being sought with an arrest warrant for using the ByLock mobile application used by FETÖ members to communicate, while B.Y. was found to be facilitating communication between M.Y. and other FETÖ members.

M.Y. previously served as a high-ranking executive in the terrorist group's Marmara regional organization, one of the FETÖ's five regional divisions in Turkey.

The police seized various digital materials and documents linked to the FETÖ, two fake identity cards and large sums of cash including 6,800 Turkish liras, $2,800 and 15,980 euros.

M.Y. and G.Y. were found to have rented the apartment under fake names.

The operation comes a few days after another high-ranking member of FETÖ was captured in a joint operation by police and intelligence services.

Reşat Nazmi Oral, a member of the group's secret network of military infiltrators was arrested in the capital Ankara. Oral allegedly played an influential role in FETÖ's July 15, 2016 coup attempt. During the coup attempt, led by FETÖ's fugitive leader Fetullah Gülen, 251 people were killed and more than 2,200 were injured.

After the coup attempt was thwarted, fugitive FETÖ members who were unable to flee the country increasingly turn to "gaybubet" houses. Gaybubet means "absence" in FETÖ jargon, and they are used by the terrorist group to hide followers who are being sought for crimes. Former members of the terrorist group who collaborated with authorities to avoid jail, say that the group mobilized to collect money to cover the expenses of fugitive members or those dismissed from their public duties for their links to FETÖ, and they stayed in hideouts provided by the terrorist group. FETÖ members pay a fraction of the rent and bills for each house.

FETÖ is accused of planting its members everywhere, from the police to the judiciary, the army and bureaucracy for years. Disguising their ties to the group, followers managed to rise to the top ranks. They became generals in the army and senior police chiefs. Through its "imams," FETÖ monitored the infiltrators and gave them orders. These so-called imams are often unassuming figures, such as a shopkeeper in a small town or a teacher, but they held immense power in the group, sometimes over police chiefs, generals and high-ranking bureaucrats.