Overnight, Turkish crime scene investigators entered the Saudi consulate in Istanbul, the last place Khashoggi was seen before vanishing on October 2, for the first time and searched the premises for over nine hours, Reuters witnesses said.
Khashoggi, a USA resident, Washington Post columnist and leading critic of the powerful Saudi crown prince, Mohammed bin Salman, vanished after entering the consulate to get marriage documents.
The shows of support came before CNN and the New York Times reported that Saudi Arabia was in fact preparing to acknowledge its role in Khashoggi's death by claiming that it was an interrogation gone wrong. Although officials agreed to the investigation, Whitson said that the message from the Saudi government is clear.
The president provided no evidence to back his comment, but said that during a phone call the Saudi King had firmly denied knowing what had happened to Mr Khashoggi.
Saudi Arabia warned it would retaliate against any sanctions imposed on the oil-rich kingdom over the disappearance of journalist Jamal Khashoggi, as more Western companies distanced themselves from the Gulf State.
US President Donald Trump earlier Monday said he had spoken with Saudi Arabia's King Salman who strongly denied the kingdom's involvement in Khashoggi's disappearance.
Mr Khashoggi, a prominent critic of Riyadh and a USA resident, disappeared on 2 October after visiting the Saudi consulate. The members arrived by unmarked police cars but said nothing to journalists waiting outside as they entered the building.
Asian stocks bounced modestly on Tuesday, gaining a toe-hold after a week of heavy losses, although increasing tensions between Saudi Arabia and the West fanned geopolitical concerns and capped gains. Turkish officials say they believe he was murdered there and his body removed.
Treasury Secretary Steven Mnuchin is still scheduled to attend the October 23 Future Investment Initiative in Saudi Arabia, White House economic adviser Larry Kudlow told Fox News.
Cleaning personnel enter Saudi Arabia's consulate in Istanbul on Monday. The team arrived at the consulate in an unmarked police auto dressed in overalls and gloves and made no comments to reporters gathered outside as they entered the building.
People walk past the Saudi consulate in Istanbul, Oct. 7, 2018.
JPMorgan Chase & Co Chief Executive Jamie Dimon became the most high-profile banker to withdraw from the event on Sunday night.
Mr Pompeo's visit comes as Turkish police investigators entered the Istanbul consulate late on Monday.
The kingdom seems to be taking on each challenge one by one, beginning with Turkey where the macabre incident took place.
Trump last week vowed to uncover the truth about what happened to Khashoggi and promised "severe punishment" for those responsible.
Khashoggi, a Saudi-born writer who contributed to the Washington Post, was highly critical of the crown prince's government and has been living in self-imposed exile in the United States for a year because of fears he would be arrested in a crackdown on dissidents.