Saudi Arabia has called allegations it killed Khashoggi "baseless".
Reports in the USA media suggest that Saudi officials are set to admit that Mr Khashoggi was killed during an interrogation that went wrong, but neither King Salman, or his son and power behind the throne, Crown Prince Mohammed, had ordered Mr Khashoggi's death.
From South Africa, however, there has been silence - raising questions about whether potential Saudi investment in state arms company Denel could be playing a role.
Khashoggi, a Saudi national and USA resident who became increasingly critical of powerful Crown Prince Mohammed bin Salman, has not been seen since he walked into the Istanbul consulate to sort out marriage paperwork on October 2. He has not been seen since. The sources said the interrogation was meant to lead to his enforced return to Saudi Arabia.
The moves by the USA executives follow similar withdrawals from the event by JP Morgan & Chase Co Chief Executive Jamie Dimon and Ford Motor Co Chairman Bill Ford on Sunday.More news: Honduras takes action against migrant caravan after Trump threatens to cut aid
Trump announced he'd dispatched Secretary of State Mike Pompeo to the kingdom - and anywhere else necessary - to get to the bottom of the apparent demise of Khashoggi, a Saudi who had been living and working in the United States.
Either a family friend, a Saudi-owned company or the state's sovereign wealth fund could bid for the Glazer family's private shares in the club valued at nearly £3billion, the report said.
Shortly after the cleaning crew entered the Saudi consulate, a team of investigators arrived in an unmarked police vehicle to begin an inspection of the building a full 13 days after Khashoggi entered to obtain marriage documents and never reemerged.
He has put forth the Saudi media's narrative of "rogue killers" as a possible scenario.
Former Army general and Central Intelligence Agency director David Petraeus, who now chairs the KKR Global Institute, has also withdrawn, according to a company spokesperson. But it's Saudi Arabia's crown prince, Mohammed bin Salman, who wields the real power in the country.More news: Supply chain on edge with iPhone XR demand
Turkish officials have told reporters that they believe Khashoggi was very likely killed or abducted within hours of his arriving at the consulate.
Late Sunday, King Salman spoke on the telephone with President Erdoğan about Khashoggi.
Turkish officials have said they believe the Saudi journalist was murdered there and his body removed, which the Saudis have strongly denied. The Saudi government, it said, would shield the prince by blaming an intelligence official for the bungled operation. There's something - you'll be surprised to hear me say that, there's something really awful and disgusting about that if that was the case so we're going to have to see.
U.S. Senator Lindsey Graham, a Republican close to Trump on some issues, called the crown prince a "toxic" figure, adding, "He can never be a world leader on the world stage". "No, we're going to try and find out". However, they have not presented any evidence to corroborate their claim and say that video cameras at the consulate were not recording at the time.
The Saudi stop is one of several Mnuchin is due to make on his Middle East visit, so he will have a chance to cancel at the last minute without scrapping the entire trip.More news: Recreational Marijuana Is Legal In Canada Today: Here Are The Rules
On Sunday, a Treasury Department spokesman told CNN, "We will be evaluating the information that comes out this week".