After he was shown into the office of the Saudi consul, Mohammad al-Otaibi, the agents seized Khashoggi nearly immediately and began to beat and torture him, eventually cutting off his fingers, the senior Turkish official said.
On Tuesday, the Washington Post scanned copies of the passports of the 15 men, who arrived in Turkey the same day as Khashoggi and have been linked to his murder. Khashoggi was a United States resident who wrote columns for the Washington Post and he was critical of the Saudi government, calling for reforms.
The disclosure comes as Turkish authorities work to substantiate publicly its allegations against Saudi Arabia before the Saudis issue a much-anticipated public explanation for his disappearance.
Analysts say Saudi officials plan to blame Khashoggi's killing on rogue elements, who allegedly acted on their own not on official orders in a desperate attempt to save the battered image of the kingdom and its Crown Prince Mohammed bin Salman.
Following the reports, U.S. President Donald Trump said Saudi Arabia's crown prince denied knowledge of what happened to Khashoggi in a phone call.
The newspaper said one of the Saudis torturing Mr Khashoggi replied: "Shut up if you want to live when you return to (Saudi) Arabia".
After his talks in Riyadh on Tuesday, Pompeo was expected in Turkey today to meet Turkish Foreign Minister Mevlut Cavusoglu.
Mr Harbi and Mr Alzahrani have the same names as two people who have been identified as members of the Saudi Royal Guard, the New York Times said.
The Crown Prince told Pompeo that the United States and Saudi Arabia "are strong and old allies".
Trump has cultivated close ties with the country's de facto leader, Crown Prince Mohammed Bin Salman, and the president has expressed doubt that Prince Mohammed is responsible for Khashoggi's disappearance or knows what happened to the journalist. Neither side has publicly shown clear evidence to back up its claims, and the two governments agreed on a joint working group to probe Khashoggi's disappearance.
Trump has previously said he does not want to halt a proposed $110 billion arms sale to Saudi Arabia - as some in Congress have suggested - because it would harm the USA economically.
Again on Twitter, President Trump yesterday tweeted: "For the record, I have no financial interests in Saudi Arabia (or Russian Federation, for that matter)".
Mr Pompeo told reporters that the regime "made a commitment to hold anyone connected to any wrongdoing that may be found accountable for that, whether they are a senior officer or official".
Turkish police had earlier spent more than eight hours searching the consulate building, taking away soil and DNA samples for further examination.
The president said Mr. Pompeo was directed to visit whatever countries were necessary to get to the bottom of it.