Ahmet Şan, the chairman of Turkey's Konyaspor football club, resigned Tuesday over his alleged links to the Gülenist Terror Group (FETÖ).
On Monday, as part of the FETÖ probe, Şan testified over his alleged use of the smartphone application ByLock. He was released after his interrogation at the Konya prosecutor's office.
The ByLock mobile app was allegedly used by FETÖ members during last year's deadly defeated coup attempt.
The mobile app is believed to have been cracked by Turkish security agencies before the coup attempt, prompting the plotters to switch to the WhatsApp messaging service but not before tens of thousands of FETÖ suspects were identified.
In a statement on the club's website, Şan denied the accusations, saying he had no connection with the "evil" organization and believed "his innocence" would be proven.
He went on to say that he had resigned from his post in order not to "harm" Konyaspor.
Meanwhile, Ömer Çatkıç, former goalkeeper of Turkey's national football team, was also arrested as part of the FETÖ probe.
According to the Turkish government, FETÖ and its U.S.-based leader Fetullah Gülen orchestrated the defeated coup of July 15, 2016, which left 250 people killed and nearly 2,200 injured.
Ankara also accuses FETÖ, of being behind a long-running campaign to overthrow the state through the infiltration of Turkish institutions, particularly the military, police, and judiciary.