Muzaffer Özcengiz, a Turkish teacher who died of heart attack in a Çorum prison on Friday, was laid to rest on Monday.

Tens of suspicious deaths have been reported since the failed coup attempt in 2016. Özcengiz was jailed after a failed coup attempt in 2016 over his links to Turkey’s Gulen group, which the Turkish government accuses of masterminding the attempt.

The group denies any involvement.

According to Mehmet Ali Aslan, a former pro-Kurdish deputy, Özcengiz has been held in solitary confinement for months: “Muzaffer Özcengiz, a former teacher who suffered from hypertension and diabetes, died of heart attack in solitary confinement in the Çorum prison. End the use of solitary confinement immediately!”

According to a report compiled by Turkey Purge editors, at least of 58 individuals, among which are police officers, prosecutors and teachers, have been found dead in Turkish prisons since a failed coup attempt on July 15,2016, causing serious concern about the fate of thousands of civilians who have been kept in jail in very poor conditions across the country.