ANKARA, Turkey (AP) — Turkey's state-run news agency says a prosecutor has concluded that a network led by a U.S.-based Muslim cleric is behind the 2016 killing of Russia's ambassador to Turkey and is seeking prison terms for the preacher and 27 others.

Anadolu Agency said Friday that the prosecutor's indictment accuses Fethullah Gulen and others of terror charges.

An off-duty police officer fatally shot Ambassador Andrei Karlov at a photo exhibition in Ankara on Dec. 19, 2016. The officer was later shot dead at the scene by police.

The prosecutor maintains that Gulen's movement — which is also accused of masterminding the failed coup in 2016 — aimed to derail relations between Turkey and Russia.

A court must accept the indictment before a trial date is set.

Gulen denies involvement in the coup.