Ünsalan Özkan, a 54-year-old former police officer imprisoned over alleged links to the faith-based Gülen movement, died of a heart attack in Ankara’s Sincan Prison on Thursday, three months before his release, the TR724 news website reported.

Özkan collapsed in the prison courtyard while playing volleyball and was later pronounced dead at a hospital on the Sincan Prison campus.

He was dismissed from the police force by an emergency decree following a coup attempt in 2016 and was arrested in October of that year. After spending 17 months in pretrial detention in the Sincan and Afyon Dinar prisons, he was sentenced to more than six years on charges of membership in a terrorist organization.

The conviction was based on witness testimony and his alleged use of ByLock, an encrypted messaging app once widely available on Apple’s App Store and Google Play that Turkish authorities claim was used as a secret communication tool for Gülen supporters.

Released pending appeal, Özkan was rearrested in 2024 after Turkey’s Supreme Court of Appeals upheld his conviction and was returned to Sincan Prison. He had been expecting conditional release in three months.

Following his dismissal from the Ankara Police Department, Özkan supported himself and his family by running a carpet-cleaning business.

He had previously been allowed to attend his father’s funeral in handcuffs.

Özkan is survived by his wife and three children, all in their 20s.

Turkish President Recep Tayyip Erdoğan has targeted followers of the Gülen movement, inspired by US-based cleric Fethullah Gülen, who died in 2024, since corruption investigations in December 2013 implicated him as well as some members of his family and inner circle. He dismissed the probes as a Gülenist conspiracy and later designated the movement as a terrorist organization in May 2016, intensifying a sweeping crackdown after a coup attempt in July of the same year that he accused Gülen of orchestrating. The movement denies involvement in the coup attempt or any terrorist activity.

According to the latest figures from the justice ministry, more than 126,000 people have been convicted of alleged links to the movement since 2016, with 11,085 still in prison. Legal proceedings are ongoing for over 24,000 individuals, while another 58,000 remain under active investigation nearly a decade later.

In addition to the thousands who were jailed, scores of other Gülen movement followers had to flee Turkey to avoid the government crackdown.