More major players in international finance and industry are pulling out of a high-profile business conference in Saudi Arabia in the wake of reports that a U.S.-based Saudi writer critical of the government disappeared and is feared dead after entering a Saudi consulate in Turkey.

The chief executive of JPMorgan Chase & Co., Jamie Dimon, had been a featured speaker at the conference in Riyadh, but the company said Monday he no longer plans on attending. BlackRock CEO Laurence Fink and Blackstone CEO Stephen Schwarzman are also canceling plans to attend the Future Investment Initiative, according to people familiar with the situation.

The conference, hosted by Saudi Arabia's Crown Prince Mohammed bin Salman, is nicknamed "Davos in the Desert." It has been billed as part of the country's efforts to modernize its economy and society. The conference is slated to feature more than 180 speakers, according to its website on Monday morning.

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The corporate cancellations come after several high-profile executives pulled out of the conference last week or curtailed their plans for doing business in Saudi Arabia, including Ford Motor Co.'s Bill Ford and Virgin Group founder Richard Branson. Technology investor Steve Case and Uber CEO Dara Khosrowshahi also backed away from projects with Saudi Arabia after the disappearance and alleged killing of journalist Jamal Khashoggi, a Saudi citizen who resides in Virginia.

The impact on relations between the U.S. and Saudi Arabia could be far reaching, if it's found that the Saudis were involved with Khashoggi's disappearance, said Michael Morrell, former acting and deputy director of the CIA and a CBS national security correspondent, on CBS This Morning.

"At the low end of the spectrum would be limited sanctions against those individuals and those entries who were specifically involved in the murder," Morrell said. "In the middle would be a delay in arms sales. and at the far end would be sort of broad sanctions against Saudi Arabia in general."

President Donald Trump tweeted Monday morning that he had spoken with the king of Saudi Arabia, "who denies any knowledge of whatever may have happened 'to our Saudi Arabian citizen'." He said Secretary of State Mike Pompeo will travel to meet with King Salman, the 82-year-old father of the crown prince.

Just spoke to the King of Saudi Arabia who denies any knowledge of whatever may have happened “to our Saudi Arabian citizen.” He said that they are working closely with Turkey to find answer. I am immediately sending our Secretary of State to meet with King! — Donald J. Trump (@realDonaldTrump) October 15, 2018

Last week, Turkish officials reportedly told the U.S. government that they have audio and video recordings proving the Washington Post columnist and dissident was killed inside the Saudi consulate in Istanbul this month. The alleged slaying threatens to derail efforts by Saudi Crown Prince Mohammed bin Salman to portray Saudi Arabia as a more open and tolerant place to visit, invest in and do business.

The kingdom has called such allegations "baseless" but has not offered any evidence Khashoggi ever left the consulate.

The 33-year-old crown prince hopes to grow his country's $500 billion sovereign wealth fund -- pounded by falling oil prices earlier this decade -- into a $2 trillion global investment fund over the next dozen years.

Virgin Group's Branson said he is suspending his work overseeing two Saudi tourism projects as well as talks with the kingdom's sovereign wealth fund about possible investments in his space ventures Virgin Galactic and Virgin Orbit.

Saudi arms deals

A member of the U.S. Senate Foreign Relations Committee said the U.S.-Saudi relations may need "to be completely revised" if an investigation finds the kingdom's government responsible for the murder of Washington Post contributor Jamal Khashoggi.

Republican Marco Rubio of Florida says that includes the multi-billion dollar arms deal that President Donald Trump wants to preserve.

Rubio told CBS' "Face the Nation" that "we can never be a voice for human rights anywhere in the world if we allow a situation like this to go forward and us do nothing about it."

The senator calls Saudi Arabia "a key leverage and hedge point against Iranian influence in the region." But, he adds, that "cannot supersede our commitment to human rights."

If the Saudis are implicated, Rubio says there would be no pro-Saudi contingent in Congress "that's going to stick with our relationship with Saudi Arabia as it's currently structured.

Rubio said he believes Treasury Secretary Steven Mnuchin shouldn't attend the investment conference in Saudi Arabia later this month. No U.S. government officials "should be going and pretending as it's business as usual, until we know exactly what's happened here," Rubio said.

But White House economic adviser Larry Kudlow says the conference will deal with terrorist financing and how to stop it, and that "at the moment," Mnuchin intends to go.

Kudlow tells ABC's "This Week" that Mnuchin "will make up his mind as the week progresses and as new information surfaces" and the investigation proceeds.