Police have released new images and video of the suspect and say they are close to identifying him.
Riot police carried out raids across Istanbul on Monday in connection with an ongoing investigation into the New Year's Day shooting at a nightclub that killed 39 people and injured 69.
Twelve people have so far been detained as part of the operation to find the gunman who opened fire at the upmarket venue in Turkey's biggest city. The gunman escaped the scene in the chaos following the attack.
Police have released new images and videos of the alleged gunman and say that they are close to identifying him.
Police say initial indications are that the attacker may be from Uzbekistan, Kyrgyzstan or Xinjiang in eastern China.
According to security experts who examined the footage of the attack which was claimed by Daesh, the suspect appeared to be professionally trained in the use of the weapon he used in the massacre.
Funeral ceremonies for the victims have been held in towns across Turkey.
TRT World's Soraya Lennie in Istanbul and Alican Ayanlar in Hatay have more.