Istanbul's chief prosecutor's office said on Wednesday journalist Jamal Khashoggi was suffocated as soon as he entered Saudi Arabia's consulate on October 2 in a pre-planned killing, and his body was then dismembered and disposed of.
It also said in a statement that no concrete results were reached in chief prosecutor Irfan Fidan's talks in Istanbul this week with Saudi public prosecutor Saud al-Mojeb.
Last week CIA Director Gina Haspel reportedly heard an audio recording of the Saudi journalist's death.
Haspel traveled to Turkey to review intelligence about the Khashoggi incident.
Saudi Arabia's public prosecutor held talks overnight with Turkish intelligence officials over the investigation into the killing of journalist Jamal Khashoggi at the Saudi consulate in Istanbul, Demiroren news agency said.
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It said Saud Al Mojeb left his hotel shortly after midnight and went to the Istanbul regional offices of Turkey's National Intelligence Agency (MIT). It did not say how long he stayed there before returning to his hotel.
Khashoggi's death has escalated into a crisis for the world's top oil exporter, which at first denied any knowledge of, or role in, his disappearance four weeks ago.
Last week Mojeb contradicted previous Saudi statements, saying Khashoggi's killing was premeditated. Riyadh says it has arrested 18 suspects, including a team sent to Istanbul hours before Khashoggi's death, but has rejected Turkey's call for their extradition.
President Tayyip Erdogan, who has demanded more information from Saudi Arabia, said on Tuesday Istanbul's chief prosecutor had asked Mojeb to disclose who sent the team from Riyadh which is suspected of involvement in the killing.
The killing of Khashoggi, a critic of de facto ruler Crown Prince Mohammed bin Salman, has put into focus the West's close relationship with Saudi Arabia - a major arms buyer and lynchpin of Washington's regional plans to contain Iran.