They offered no specific evidence to back up the account.
Saudi Arabia denies involvement in Khashoggi's disappearance, and the Trump's administration's response has been far more cautious than that coming from Capitol Hill. Turkish prosecutors are already looking into the case.
Unlike in other stories where some middle narrative is likely to be true, however, the options here are very stark.
"As the President has conveyed, the United States is concerned by his disappearance".
USA officials are aware of The Post's report about Khashoggi but can not confirm it, and do not know where Khashoggi is, a senior US official told the Post on Saturday. The experts are Bernard Duhaime, who researches involuntary disappearances; David Kaye, who specializes in freedom of expression; and Agnes Callamard, who focuses on summary executions. In his dealings with Canada, including a withdrawal of investment, the Saudi ruler has shown he does not tolerate criticism of his country's human rights record. He said that The Post was committed to discovering the truth and that if the investigation showed any Saudi government involvement, the news organization would view it as a flagrant attack on one of its journalists.
Kurtulmus called the journalist's disappearance a "dire, grisly and scary event".
He also called for Saudi Arabia to provide evidence, like surveillance footage, that proves the journalist left the consulate building safely.
"We have nothing to hide", the prince said, claiming that the journalist exited the building "after a few minutes or one hour".
European Union foreign affairs chief Federica Mogherini says the bloc stands side-by-side with the United States in urging authorities to clear up the journalist's disappearance in Turkey a week ago. The Associated Press has reported on secret prisons in Yemen run by UAE-backed forces where detainees faced physical and sexual abuse, as well as how Emirati forces cut secret deals with al-Qaida militants to get them to abandon territory. "I do not recall any case of this kind whereby a journalist is killed inside a diplomatic mission in either the 20th or the 21st century", he said. "We are fully aligned with the United States on this, with the USA position on this".
Mr Trump's position is in line with the State Department whose spokeswoman Heather Nauert reiterated on Monday that the United States is "not in a position to confirm these reports, but we are closely following the situation".
Rights office spokeswoman Ravina Shamdasani says it would be "truly shocking" if reports of the death of Saudi journalist Jamal Khashoggi are confirmed. The prominent critic of the country's policy in the Yemen war was an editor of a newspaper in Saudi Arabia and adviser to the country's former head of intelligence.
She added: "Although this incident could potentially fuel a political crisis between the two nations, let us not lose sight of the human aspect of what happened".
On Sunday, the Saudi Press Agency released a statement, quoting an official at Saudi Arabia's consulate in Istanbul, who "strongly denounced these baseless allegations, and expressed his doubt that they came from Turkish officials that are informed of the investigation or are authorized to comment on the issue". The picture bore a date and time stamp, as well as a Turkish caption saying that Khashoggi was arriving at the consulate.
In an article published by Al-Jazeera this week, journalist and analyst Bill Law described Khashoggi as "a brilliant journalist with a fiercely independent mind but with sufficient pragmatism to know just how close to the red lines he could go". Khashoggi disappeared immediately afterward.
"The ambassador was told that we expected full cooperation during the investigation", the source said.
A Saudi columnist remained missing as supporters rallied outside the Saudi consulate in Istanbul calling for his "release" despite Riyadh's denials that he was being held there.
According to some media reports, Khashoggi, 59, has been killed inside the Saudi consulate.