ANKARA, Turkey (AP) — A Turkish court has issued arrest warrants for a U.S.-based Muslim cleric and seven other people for their alleged involvement in the killing of Russia’s ambassador to Turkey, the country’s state-run news agency reported Monday.

An off-duty police officer fatally shot Ambassador Andrei Karlov while he was speaking at the opening of a photo exhibition in the Turkish capital on Dec. 19, 2016. The officer, Mevlut Mert Altintas, was later shot dead at the scene by police.

The court in Ankara issued warrants for cleric Fethullah Gulen and seven people allegedly tied to his religious movement on charges of attempting to “destroy the constitutional order” and “pre-meditated murder,” Anadolu Agency reported.

Turkish authorities have alleged that Karlov’s killer had links to Gulen, whom Turkey also accuses of masterminding a failed July 2016 coup and wants extradited from the United States. Gulen, who has lived in the U.S. since 1999, has denied involvement in the coup attempt.

Turkey believes that Gulen’s movement was also behind Karlov’s assassination, maintaining that it was aimed at derailing warming relations between Turkey and Russia.

Nine people, including three former police officers, have already been arrested over the killing.

The warrants were issued as Russian President Vladimir Putin prepares to make a two-day trip to Ankara. Putin is scheduled to meet with Turkish President Recep Tayyip Erdogan on Tuesday. They are set to be joined by Iranian President Hassan Rouhani on Wednesday for a summit on Syria’s future.

Associated Press photographer Burhan Ozbilici won the 2017 World Press Photo competition for his image of the gun-wielding policeman standing over the body of the Russian ambassador immediately after he shot Karlov.