Twenty-eight people went on trial Tuesday for their involvement in the 2016 assassination of Russian Ambassador to Turkey Andrei Karlov, reported The Associated Press. Among the accused are US-based cleric Fethullah Gulen, whom Turkey blames for a failed coup the same year. Nine of the suspects appeared in court and four via video-conference, said the Anadolu Agency. Gulen is being tried in absentia. An off-duty police officer fatally shot Karlov at a photo exhibition in Ankara on December 19, 2016. The officer was later shot dead at the scene by police. Turkish prosecutors say Gulens network was behind the killing, which they say aimed to derail warming ties between Turkey and Russia. Prosecutors are seeking life prison sentences for some of the defendants and maximum 15-year terms for others. Gulen has denied involvement in the coup and in Karlovs killing.