Turkish officials say they believe he was murdered there and his body removed, which the Saudis strongly deny. Theories of "rogue elements" & "investigations gone wrong" were propounded by US President, Donald Trump.
Pompeo met King Salman and Crown Prince Mohammed bin Salman in Riyadh to discuss the incident, which has caused global outrage and brought renewed attention on the authoritarian kingdom's human rights record.
During Pompeo's first trip as secretary of state in April, the crown prince kept him waiting several hours for an appointment because he was presiding over the groundbreaking of an entertainment center. "We deal with bad people all the time, but this is in our face", said Graham.
Pompeo was to have a dinner Tuesday night with Prince Mohammed and was expected to fly to Turkey on Wednesday.
Turkish authorities have an audio recording indicating that Khashoggi was killed in the consulate, Turkish sources have told Reuters, and shared evidence with countries including Saudi Arabia and the United States.
Earlier in the day, United Nations human rights chief Michelle Bachelet said the "inviolability or immunity" of people or premises granted under the 1963 Vienna Convention on Consular Relations "should be waived immediately".
Saudi Arabia has said it would retaliate against any pressure or economic sanctions.
Turkish officials have said privately that Khashoggi was killed in the consulate on October 2 after he arrived to obtain papers that would have allowed him to marry his Turkish fiancée, Hatice Cengiz.
The residence of Saudi Arabia's Consul General Mohammad al-Otaibi is pictured in Istanbul.
"Nothing happens in Saudi Arabia without MBS knowing it".
"Here we go again with you're guilty until proven innocent", Trump told AP in an interview. It sounded to me like maybe these could have been rogue killers.
Earlier Erdogan said that the Turkish intelligence is investigating the disappearance of the Saudi reporter Khashoggi.
On Tuesday, US Secretary of State Mike Pompeo held crisis talks with King Salman in Riyadh, as the kingdom tried to quash the fallout from the presumed murder.
"This guy has got to go", he concluded, saying bin Salman, the son of King Salman bin Abdulaziz Al Saud, has "tainted" the country's image.
Summit, dubbed as "Davos in the Desert" is scheduled for October 23-25 in Riyadh, Xinhua news agency reported.
Among them were Uber CEO Dara Khosrowshahi, former AOL CEO and venture capitalist Steve Case, J.P. Morgan Chase CEO Jamie Dimon, Ford Chairman Bill Ford, and Google Android creator Andy Rubin.
US Treasury Secretary Steven Mnuchin said he still plans to attend but would "take (it). into account" if more information came out.
Coming exactly one year after Panama Papers Maltese anti-corruption journalist, Daphne Caruana Galizia was killed in a auto bomb attack, also Bulgarian TV Journalist Viktoria Marinova was murdered and raped in the northern city of Ruse shortly after leaving studio.
Trump previously warned of "severe punishment" for the kingdom if it was found to be involved in Khashoggi's disappearance, which has spooked investors in Saudi Arabia and SoftBank, a Japanese firm that manages tens of billions of dollars for the kingdom.
But he has also made clear he is reluctant to curb all-important arms sales to Saudi Arabia.
Turkish sources have told MEE that they do not trust the Saudis, and expect them to hinder the investigation.