President Trump pledged Wednesday to meet with the fiancee of disappeared dissident Saudi journalist Jamal Khashoggi, who vanished after entering the Saudi consulate in Istanbul last week, and warned Saudi Arabia that he would get to the bottom of the situation.

Trump told reporters in the Oval Office that he intends to host Khashoggi's fiancee at the White House, and that he had spoken with "the highest level" of the Saudi government.

"We cannot let this happen, to reporters, to anybody," Trump said.

Khashoggi, a critic of Saudi Arabia's powerful crown prince Mohammed bin Salman, most recently worked as a columnist for the Washington Post, and is feared murdered after entering the consulate on Oct. 2.

Saudi officials say Khashoggi left shortly after an appointment for marriage-related paperwork, as his fiancee waited outside. No evidence of him departing has emerged, as the story attracted international attention.

[Opinion: Add Jamal Khashoggi to a very long list of Saudi Arabia's civilian murders]

Referring to the journalist's fiancee, Trump said: "His wife wrote us a letter. And addressed it to my wife and myself. And we're in contact with her now, and we want to bring her to the White House. It's a very sad situation. It's a very bad situation. And we want do get to the bottom of it."

Trump said "I hope he's not" dead, which Turkish news outlets report is the case. Local media reported on a group of 15 Saudis who arrived in the city at about the time of his disappearance, describing the group as an assassination squad.

"People saw him go in and didn't see him come out as they understand it. We're going to take a serious look at it. It's a terrible thing," Trump said.

The White House released a statement following Trump's remarks, saying national security adviser John Bolton and presidential adviser and son-in-law Jared Kushner spoke with the crown prince Tuesday, and that Secretary of State Mike Pompeo had a follow up call with the prince.

"In both calls they asked for more details and for the Saudi government to be transparent in the investigation process," the White House statement said.

Trump did not answer a shouted question Wednesday afternoon about whether he personally spoke with the crown prince.

At the morning Oval Office event, Trump said the U.S. would work with Turkish officials to learn more about what happened.

Trump declined to comment on Saudi Arabia imprisoning another dissident journalist, Raif Badawi.

Canada's foreign ministry demanded the release of Badawi and his sister in August, resulting in a furious reaction from Saudi officials, who expelled Canada's ambassador and ordered a mass-withdrawal of Saudi investments.

Badawi, former editor of the website Free Saudi Liberals, was sentenced to 10 years in prison and 1,000 lashes in 2014. His lashes were suspended following international outcry.

"When you say release the journalist, who are you talking about?" Trump asked. When told, he said, "That I'd have to look into. I'm not familiar with that."