The Istanbul prosecutor's office said of the talks, which took place on Monday and Tuesday: "Despite our well-intentioned efforts to reveal the truth, no concrete results have come out of those meetings".
Turkish President Recep Tayyip Erdogan has also called on Riyadh to disclose the identity of an alleged local collaborator said to have been involved in disposing of Mr Khashoggi's body. After this, the statement alleges, Saudi officials proceeded with dismembering Khashoggi to secretly transport his body and cover up the killing.
He added that "depending on the results that will be announced (of the Turkish and Saudi investigations), we will implement the necessary sanctions against those guilty". He was last seen entering the building of the Embassy of Saudi Arabia in Istanbul.
Hatice Cengiz, the fiancée of slain Saudi journalist Jamal Khashoggi.
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On Oct. 20, Saudi Arabia confirmed Khashoggi died Oct. 2 after entering the Saudi consulate in Istanbul, Turkey, to obtain documents for his planned marriage.
A critic of the Saudi royal family, Khashoggi had been living in exile in the States.
Turkey says an "inspection" of the consulate is expected to take place later on Monday, almost two weeks after Saudi journalist after Jamal Khashoggi disappeared there.
The dissident reporter disappeared after going to the the diplomatic mission on October 2.
Saudi Arabia has so far denied the extradition of 18 suspects detained in Riyadh, but officials insist the kingdom will bring them to justice once the investigation is complete.
Al-Muajab held talks overnight with Turkish intelligence officials, Turkey's Demiroren news agency reported.
Khashoggi, known for his criticism of Saudi policies, had been working as a columnist for The Washington Post.