Turkey has said the Islamic State of Iraq and the Levant (ISIL) is the prime suspect in the suicide bombings that killed at least 97 people in Ankara as anger grows about the government's inability to have prevented the attack.
The twin bomb blasts at a peace rally on Saturday have raised tensions in Turkey, three weeks before snap elections are due on November 1.
Prime Minister Ahmet Davutoglu said Saturday's attack, the worst of its kind on Turkish soil, was intended to influence the outcome of the polls - which President Recep Tayyip Erdogan hopes will restore a majority the ruling AK party lost in June.
Officials say there is no question of postponing the vote.
"If you consider the way the attack happened and the general trend of it, we have identified Islamic State as the primary focus," Davutoglu told Turkey's NTV television on Monday, referring to ISIL.
"It was definitely a suicide bombing ... DNA tests are being conducted. It was determined how the suicide bombers got there. We're close to a name, which points to one group."
Turkey is vulnerable to infiltration by ISIL, which holds swaths of Syrian land abutting Turkey where some two million refugees live.
But there has been no word from the group - usually swift to publicly claim responsibility for any attack it conducts - over the Ankara bombing or two very similar incidents earlier this year.
Saturday's attack came in less than three months since a suicide bombing blamed on ISIL, also against peace activists, in the town of Suruc on the Syrian border that killed 33 people.
Funerals were held across the country on Monday for many of the victims of Saturday's bombing and flags flew at half-mast across the nation during three days of national mourning.
Opponents of Erdogan, who has led the country over 13 years, blame him for the attack, accusing the state, at best, of intelligence failings, and at worst: of complicity by stirring up nationalist, anti-Kurdish sentiment.
Hundreds chanting anti-government slogans marched at a mosque in an Istanbul suburb for the funeral of several of the victims, attended by Selahattin Demirtas, leader of the pro-Kurdish parliamentary opposition, the Peoples' Democratic Party (HDP), which says it was the target of the bombings.
Riot police with water cannon and armoured vehicles stood by as the crowd, some chanting "Thief, Murderer Erdogan" and waving HDP flags, moved towards the mosque in the working-class Umraniye neighbourhood of Istanbul.
Meanwhile, at Ankara's Medical Forensic Authority Complex, many family members were still helping authorities identify victims of the attack.
Kurdish man Fadil Seylo, waiting to help identify his two nieces, who are believed to have been killed in the blasts, told Al Jazeera that he could not understand how such an attack could have been carried out.
"In the heart of the capital - in Ankara - and these explosions occur? This just raises so many questions," he said.
"How can anyone say there is no security weakness when it comes to this situation? How did these people bring the bombs here? How did they enter the square? How did they detonate the bombs?
"We lived together for one thousand years - how come today they call us separatists? We are just pro-peace; we are just living for peace - dying for it. And even in our death, we are asking for peace and peace only."
Farmer Mecbure Ceylan, whose daughter is thought to have died in the attack, said Kurds were being treated as second-class citizens by the government.
"My daughter came here for a peace rally. Did she have a gun in her hand? No. She came empty-handed. She just came to ask for peace," she said.
"I have been here for the last three days. I have gotten no information whatsoever. Is my daughter dead or alive? If she is dead, then show me her body - show me my flesh and blood. No one here is helping."
The HDP, one of the groups that had organised the rally, said it believes the death toll now stands at 128.