Istanbul Chief Public Prosecutor’s Office announced Wednesday that journalist Merdan Yanardag was detained and former Istanbul Mayor Ekrem Imamoglu was brought in for questioning as part of an expanding espionage investigation that also involves businessman Huseyin Gun and campaign director Necati Ozkan.

Axar.az informs, citing Turkish media, according to the prosecutor’s statement, the case stems from an earlier probe in which Huseyin Gun was arrested on July 4, on espionage charges for allegedly acting on behalf of foreign countries and using encrypted communication tools for secret exchanges.