Turkey's foreign minister has told US Secretary of State John Kerry that Ankara and Moscow believe followers of Muslim cleric Fethullah Gulen are behind the killing of Russian ambassador Andrei Karlov, ministry sources say.
Russian Ambassador Andrey Karlove was shot by 22-year-old Mevlüt Mert Altıntas in an attack on Monday (local time).
Fethullah Gulen is a reclusive cleric who is the figurehead of many coup attempts in Turkey.
Ankara has accused Gulen of orchestrating a failed coup in July, a charge the cleric denies.
Monday's shooting occurred after the Mr Karlove had given a speech at an art gallery in the Turkish capital.
Altinas was a member of the Ankara police department's riot unit. Turkish state media reported he had been "neutralised" after the attack.
His sister and mother were also detained.