Turkish investigations into a bombing apparently carried out by military intelligence agents are likely to become a test of the country's reform process, as European officials this week called for justice to be done. "Severe sanctions must be taken against those responsible for such provocation," the European commissioner for enlargement, Olli Rehn, said.
The scandal began on November 9 when an explosion tore through a bookshop in Turkey's most south-easterly town, Semdinli, killing one man. It was the 17th bomb attack in the remote Kurdish region in two months. The others remain unsolved, blamed on the Kurdish separatist PKK which declared war last summer after a five-year ceasefire.
This time local people caught the suspected bomber as he attempted to flee in a car with two other men. Investigations showed him to be a former PKK guerrilla turned informer. His two colleagues were members of Turkey's shadowy paramilitary police intelligence service, JIT.
Their car contained machine guns, grenades identical to the one used in the attack and a sketch map showing the bookshop's location.
The revelations brought back memories of the darkest days of the PKK's war against the state, when security forces had near total control over the south-east. Eighty per cent of the 700 assassinations carried out there between 1990 and 1996 were the work of JIT, according to a former operative interviewed in a documentary released this spring. None of the culprits has been brought to justice.
With a half an eye on the European Union, Turkish leaders say they are determined to shed light on an affair many see as an attempt by anti-democratic forces to destabilise Turkey's progress to EU membership.
"Nobody should expect favouritism from us", prime minister Tayyip Erdogan said, following a visit to Semdinli. "We will pursue this issue to the very end."