A picture taken just before Russia's ambassador to Turkey Andrei Karlov was killed captures the suspect standing right behind him.
According to reports, the 62-year-old ambassador had been speaking at an exhibition in Ankara, Turkey, when a man fired at least eight shots.
The Turkish interior minister said the gunman was a policeman.
The gunman shouted in Turkish: "Don't forget Aleppo, don't forget Syria" as well as "we are the descendants of those who supported the Prophet Mohammad, for jihad." Russia has backed Syrian President Bashar Assad throughout the nearly six-year conflict, while Turkey has supported Assad's opponents.
He was also pictured gesturing with the gun after the shooting.
Turkey's Anadolu news agency reported that after shooting the ambassador, the gunman climbed to the second floor of the same building and a 15-minute shoot-out with police ensued before he was killed.