Şükrü Tuğrul Özşengül, a former lecturer at the Turkish National Police Academy has died of heart attack in Istanbul’s notorious Silivri Prison, according to Turkish media.

The 54-year-old man reportedly underwent a heart surgery in May 2020. He was later given a medical report that said he was physically fit to remain in prison.

Ozsengul was accused by the Turkish government of having links to the Gulen group, which is accused of masterminding a coup attempt in 2016. The group denies any involvement.