Sixteen defendants, including prominent Gülenist Terror Group (FETÖ) member Şahin Söğüt, were present at the trial in Ankara Second High Criminal Court along with their defense lawyers. Four others are participating in the proceedings via video stream from prison.
Karlov was killed on Dec. 19, 2016, by Mevlüt Mert Altıntaş, an off-duty police officer with links to FETÖ, in an art gallery in the capital Ankara.
The hearing, which is being covered by foreign press members, began with the identification of the defendants.
The 28 suspects indicted in the case face numerous charges including "attempting to eliminate the constitutional order," "aggravated murder for the purpose of terrorism," "membership in an armed terrorist organization."
FETÖ and its leader Fetullah Gülen are the prime suspects in the case. Along with Gülen, Şerif Ali Tekalan and Emre Uslu are prominent figures from FETÖ included in the indictment. All are currently living as fugitives in the United States.
Altıntaş was killed in a shootout with police in the gallery after the assassination. The indictment by the Chief Public Prosecutor's Office in Ankara detailed his connections to FETÖ, including Şahin Söğüt, an arrested member of the group who is accused of being a "big brother" or handler for Altıntaş on behalf of FETÖ. It was Söğüt who instructed Altıntaş to carry out the murder, according to investigators.
Security forces also arrested Timur Özkan, the curator of the exhibition Karlov was attending at the art gallery when he was murdered and Hayreddin Aydınbaş, the owner of a media company, for their links to FETÖ and the murder. Nine others including four police officers were also arrested over the murder.
The indictment includes digital evidence showing Altıntaş's connections to FETÖ. The evidence shows Şahin Söğüt met Altıntaş 10 days before the assassination and the same day, Altıntaş did online research about Russia. Other evidence shows connections between Özkan and Tekalan, a fugitive senior FETÖ member who is currently serving as a president of a U.S. university run by the terrorist group. Tekalan and Özkan had financial ties according to prosecutors.
Şahin Söğüt, his wife Ayşe Söğüt and Özkan are present in the Ankara court, while Aydınbaş is participating from prison.
Emre Uslu, a journalist who fled to the United States after an arrest warrant was issued by Turkey in a separate case, is accused of distracting suspicion from FETÖ's role in the murder on social media.
Prosecutors say FETÖ sought to derail Turkish-Russian relations with the murder. The assassination was at a time of thaw between strained Turkish and Russian relations. Since the murder, Ankara and Moscow gradually made progress in rebuilding their ties that were disrupted by the 2015 downing of a Russian fighter jet over the Syrian border by the Turkish military.