Earlier on the same day, Trump tweeted that Khashoggi is not a USA citizen and "I am immediately sending our Secretary of State to meet with King!"
A joint Saudi-Turkish team has entered the Saudi Consulate in Istanbul to search it, almost two weeks after the disappearance of Saudi journalist Jamal Khashoggi.
The Washington Post reported in recent days that the Turkish government informed US officials it was in possession of video recordings that prove Khashoggi was killed inside the consulate, but have not made them public.
"There would be ways of saying that this was a rendition gone wrong and that this whole operation was rogue and wasn't approved at the highest level", he said.
'He said it very strongly, ' Trump said when pressed to say whether he believed the Saudi king.
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. "Maybe I don't want to get into his mind, but it sounded to me like maybe these could have been rogue killers - I mean, who knows?" The Times report cited an unnamed person said to be familiar with the Saudi plans.
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He acknowledged the feeling "may be a more emotional impression than a rational one". Brussels has been far more calm coming out of the summit than on past occasions.
Also on Monday, investigators entered the Saudi consulate in Istanbul.
Turkish intelligence officials say they have audio and visual evidence that shows he was killed inside the consulate.
While the search was being carried out on Tuesday, CNN and the New York Times reported that Saudi Arabia was preparing to acknowledge Khashoggi's death in a botched interrogation.
Then channel BeoutQ, allegedly based in Saudi Arabia, apparently started pirating beIN Sport's coverage of the English top flight.
He said Bangladesh is following the news of the disappearance. Khashoggi's body was reportedly dismembered and smuggled out of the consulate building.
"The Board of Governors has chose to decline any funding from the Saudi government and to keep the matter under active review pending the outcome of the investigation into the case of Mr. Jamal Khashoggi", the group said Monday in a statement to BuzzFeed News.
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".
A defiant Saudi statement on Sunday said the kingdom rejects any "threats and attempts to undermine it, whether by threatening to impose economic sanctions, using political pressures, or repeating false accusations".