Turkey on Monday marked the seventh anniversary of the bloodiest terrorist attack in its history, but many of the Islamic State (IS) suspects charged over the bombing that killed 103 people in Ankara have yet to be brought to justice.

Sixteen suspects accused of organizing the attack and leading IS activities in Turkey remain on the run, as lawyers for the victims' families blame neglect of duty on the part of the authorities for the failure to hunt down the fugitives and prevent the attack in the first place.

Two suicide bombers — both Turkish nationals who spent time with IS in Syria — blew themselves up in a crowd converging on the capital’s main train station in Ankara on Oct. 10, 2015, at a rally for a peaceful settlement to the Kurdish conflict. In addition to the 103 dead, nearly 500 people were injured.

In a statement on the eve of the anniversary, the October 10 Lawyers Commission — a group formed by attorneys involved in the case — accused the state of “not lifting a finger” to punish those involved in the attack. “Our requests to the courts have been [routinely] denied. The required measures are not being taken to capture the fugitive suspects. Prosecutors have failed to act on our criminal complaints against IS members who are not suspects in the case but whose role in the massacre has become evident. Nothing has been done regarding public servants [suspected of neglecting their duties],” the statement said.