Turkish Prime Minister Ahmet Davutoglu says the Islamic State (IS) extremist group is the focus of a probe into a twin suicide bombing.
At least 97 people were killed in the explosions in the Turkish capital, Ankara, on October 10.
Speaking to Turkish broadcaster NTV on October 12, Davutoglu also said investigators were close to identifying one of the suspects through DNA testing.
Davutoglu said the attack was an attempt to influence the outcome of parliamentary elections due on November 1.
He said necessary steps would be taken if security failures were found to have contributed to the bombing.
The two blasts happened seconds apart as hundreds gathered for a march organized by pro-Kurdish activists and civic groups to protest over a conflict between Turkish security forces and Kurdish militants in the southeast.
The pro-Kurdish People's Democratic Party has put the death toll at 128. Davutoglu's office has said 97 people were killed.