Turkey’s main opposition has revived questions over the gruesome execution of two Turkish nationals by the Islamic State (IS) in Syria, almost six years after a video showing the pair being burned alive shook the nation to its core.

Kemal Kilicdaroglu, head of the Republican People’s Party, visited the family of one of the victims this week, pledging to take the issue to parliament. “What upsets me the most is that the army and the government made no statement about the incident after it reverberated on social media,” he said. 

The authorities responded with silence to the execution video, shared by IS-linked accounts in December 2016, that showed two young Turkish-speaking men clad in military camouflage being burned alive. 

One of the victims — Sefter Tas, a soldier abducted from a border area the year before — has been confirmed dead. According to official records, the other victim — Fethi Sahin — is still alive. Authorities have yet to shed light on the execution and punish its perpetrators, even though several suspects — most of them Turkish nationals — have emerged from IS-related court cases over the years.