Turkish authorities have detained the owner and chief executive of Asan Group, a defense and construction company, as part of a military espionage investigation, prosecutors in Istanbul announced late Wednesday.

The suspects, identified as company owner Emin Öner and CEO Gurkan Ogumus, are accused of involvement in military espionage activities and alleged ties to the network of U.S.-based cleric Fethullah Gülen, whom Ankara blames for orchestrating the failed 2016 coup attempt.

Prosecutors said searches were conducted at the suspects’ homes and offices. Meanwhile, Turkey’s Savings Deposit Insurance Fund (TMSF) has taken control of 10 companies operated by the Asan Group, placing them under trusteeship.

The investigation is ongoing, authorities confirmed.