MOSCOW, December 21. /TASS/. Turkish Foreign Minister Mevlut Cavusoglu told his US counterpart John Kerry that the movement of Fethullah Gulen was behind this week’s assassination of the Russian ambassador in Turkey, the official Anadolu news agency reported Tuesday citing diplomatic sources.

Turkey sees the movement of Gullen, a former cleric and opposition leader who has lived in the United States for more than a decade, as the leading force behind July’s failed military coup in the country.

When asked to comment on the possible involvement of Gullenists into the killing, US Department of State spokesman John Kirby replied: "I don’t know and I don’t think you know what the motivations were behind this individual."

"We need to let the investigators do their job. That we need to let them - let the facts and the evidence take them where it is before we jump to conclusions," Kirby said, adding that any notion that the United States was in any way supportive of the assassination or was indirectly involved in it was "absolutely ridiculous."

In a readout of Kerry's call with Cavusoglu Tuesday, Kirby said that the secretary "offered US assistance to the investigation into the horrific murder of Russian Ambassador to Turkey Andrey Karlov."

An armed man whom the police identified later as Mevlut Mert Altintas, 22, a former police officer, opened indiscriminate fire on Monday in an arts gallery in Ankara where Ambassador Karlov was opening an exhibition of Turkish photographic works featuring Russia. He received a gunshot wound, of which he died at hospital later.

Turkish officials said the attacker was eliminated on the spot. Apart from the ambassador, he wounded three more people.