According to The Washington Post, where Khashoggi was a contributor, he visited the Saudi consulate in Istanbul last week to get a document for his upcoming wedding.
Aktay went on to say Turkish authorities believe a group of 15 Saudi nationals were "most certainly involved" in the journalist's disappearance. He had been living in the United States since past year, in self-imposed exile, in part due to the rise of Saudi Crown Prince Mohammed bin Salman, who has shown little tolerance for criticism.
"We wouldn't normally broadcast an off-air conversation, but we've decided to make an exception, in light of the current circumstances", the British broadcaster said in a note published with the recording.
"The initial assessment of the Turkish police is that Mr. Khashoggi has been killed at the consulate of Saudi Arabia in Istanbul".
Kislakci also alleged, based on conversations with officials he did not name, that Khashoggi was made to "faint", then was dismembered.
No exact timeframe was given for when the search would take place.
Khashoggi, a columnist for The Washington Post, went into self-exile previous year citing threats to his life from the Saudi royal family.
The U.S.is concerned about Khashoggi's whereabouts, Nauert said, and would like to see the Saudi government conduct a thorough and transparent investigation into what happened to him. "It has been conveyed to him that we expect full coordination in the investigation process", the official said.
Khashoggi, 59, was likely tortured then murdered at the Saudi Arabian consulate in Istanbul, Turkey some time after October 2 when he entered the consulate.
"I have to find out what happened", Mr Trump added. Its passengers checked into two hotels near the consulate and booked rooms until October 5.
"Deeply troubled to hear reports about Saudi Arabian journalist Jamal Khashoggi".
Saudi authorities have said they do not have security footage from that day.
On his first worldwide trip as president, Trump visited Saudi Arabia and announced $110 billion in proposed arms sales.
Trump, in an interview with the Fox News "Fox & Friends" program, also called U.S. -Saudi relations "excellent".
Saudi Arabia's Crown Prince Mohammed bin Salman said this week that the kingdom would allow Turkey to search the consulate for Khashoggi.