On Wednesday, the Turkish police detained and questioned five suspects, however later three of them were released, including two under a recognizance not to leave.
According to the media outlet, Baser is allegedly linked to the movement of Islamic cleric Fethullah Gulen (FETO), suspected by Ankara of masterminding the July 2016 coup attempt and outlawed in the country.
Andrey Karlov was shot and killed at an art gallery exhibition opening in Ankara on December 19. Three more people were injured in the shooting. The gunman was killed at the scene by the police. The Russian Foreign Ministry said it considered the attack a terrorist act.