Trump has said he's unwilling to jeopardize U.S. arms sales to Saudi over the Khashoggi case, but he's also repeatedly promised to hold the perpetrators accountable.
"I don't think any of our government officials should be going and pretending it's business as usual until we know exactly what's happened here", Rubio said. "This is very important to get to the bottom of it", Trump said.
Saudi Arabia has begun an internal investigation into the disappearance of a prominent journalist at its Istanbul consulate and could hold people accountable if the evidence warrants it, according to a Saudi official.
The kingdom has so far publicly denied involvement in his disappearance.
Turkish officials allege Khashoggi, a critic of the Saudi regime living in the USA, was killed in the compound. The company negotiated the deal in January, as Saudi Crown Prince Mohammed Bin Salman embarked on an ambitious plan to invest in Hollywood and develop a domestic entertainment economy.
The Journal, like CNN, said the Saudi statement has not been finalized.
Trump demurred on whether or not he believed the denial, explaining that he was just relaying what he was told, but suggested that the Saudis may believe Khashoggi was killed by rogue agents.
Mr Trump had earlier tweeted to say that he had spoken with Salman and that he was sending U.S. secretary of state Mike Pompeo to Riyadh. Senators from both political parties have called for sanctions against Saudis responsible for Khashoggi's disappearance. Saudi Arabia, meanwhile, said King Salman thanked Erdogan "for welcoming the kingdom's proposal" for forming the working group.
The New York Times reported that the Saudi royal court would soon put out a narrative that an official within the kingdom's intelligence services - who happened to be a friend of Prince Mohammed - had carried out the killing.
It comes after oil prices rose following Saudi Arabia's thinly veiled threat yesterday to cut production if the United States imposes sanctions amid growing global tension over the disappearance. 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.
A Turkish diplomatic source earlier said a joint Turkish-Saudi team would search the building - the last place Khashoggi was seen before he vanished on October 2.
Mr Trump's comments comes after Washington and Riyadh engaged in a war of words over the weekend about Khashoggi, a Saudi-born journalist who has been living in self-imposed exile in the United States for the past year.
Avram is due to attend the Future Investment Initiative conference in Riyadh later this month, along with leading bankers and investors from around the world and key figures from the Saudi administration.
But US Treasury Secretary Steven Mnuchin said on Saturday that he still plans to attend the Saudi conference. There is even a popular rumour that what happened in Istanbul is all a plot by Qatar and Turkey to discredit the blameless Saudi kingdom.