Turkish prosecutors have ordered the exhumation of former National Intelligence Organization (MIT) official Kaşif Kozinoğlu, who died in prison in 2011, as authorities reopen an investigation into the circumstances surrounding his death.

The Silivri Chief Public Prosecutor’s Office ordered Kozinoğlu’s remains to be exhumed from Hekimbaşı Cemetery in Istanbul’s Ümraniye district in the coming days. Tissue samples will be collected for toxicological and chemical testing as investigators seek to determine whether he may have been given substances other than his prescribed medication.

Investigators are expected to focus particularly on Coraspin and vitamin supplements Kozinoğlu reportedly requested shortly before his death. The new examinations will also revisit claims concerning the original autopsy process and allegations surrounding an email sent to his lawyer after his death that reportedly disputed the initial heart attack explanation.

The latest development comes after prosecutors recently reopened the investigation into Kozinoğlu’s death, which has remained the subject of controversy for nearly 15 years.

Authorities previously issued detention warrants for 11 people who were working at the prison at the time of Kozinoğlu’s death. Ten suspects were detained, while another was reported to have fled the country.