Saudi Arabia are preparing a report that will acknowledge that Saudi journalist Jamal Khashoggi's death was the result of an interrogation that went wrong. Until now, Riyadh has not allowed Turkish investigators to search the consulate - officially Saudi territory - with reports both sides were at odds over the conditions.
Within days of his disappearance, Turkish officials - anonymously and without releasing evidence - told reporters that they were certain the veteran journalist was killed inside the building.
Trump's comments came after a telephone conversation with King Salman, father of the crown prince, the first such talks since the crisis erupted.
Hours prior, President Trump announced in a tweet that he spoke with Saudi Arabia's King Salman about Khashoggi. Turkish officials have said they fear a Saudi hit team killed and dismembered Khashoggi, who wrote critically of Saudi Crown Prince Mohammed bin Salman.
Secretary of State Mike Pompeo will travel to Riyadh today, the State Department said, adding that 'the president has called for a prompt and open investigation'. He was joined on the plane by David Hale, the under secretary for political affairs, and Tim Lenderking, a deputy assistant secretary for Arabian Gulf affairs, among others.
In protest of Khashoggi's disappearance, several US businesses leaders have pulled out of next week's Future Investment Initiative in Riyadh, dubbed "Davos in the Desert", after the annual meeting of world economic interests in Switzerland.
"The king firmly denied any knowledge of it", Trump told reporters after speaking with King Salman.
The comments marked a break from the Trump administration's previous refusal to speculate over the fate of Khashoggi and came as the USA president is under growing pressure to take action on the case.
Permission apparently came after a late Sunday night call between King Salman and Turkish President Recep Tayyip Erdogan.
The statement did not elaborate but a column published in English a short time later by the general manager of the Saudi-owned Al-Arabiya satellite news network suggested Saudi Arabia could use its oil production as a weapon.
Three major lobbying firms in Washington - Glover Park Group, the Harber Group and BGR Group - have also cut ties to Saudi Arabia amid Khashoggi's disappearance. Pompeo is expected to go to Riyadh and later visit Turkey.
Trump has threatened "severe punishment" if it turns out Khashoggi was killed in the consulate, although he has ruled out cancelling arms deals worth tens of billions of dollars with Saudi Arabia. He said the USA was working with Saudi Arabia and Turkey to figure out what happened.
However, given the close political and economic links between the United States and Saudi Arabia it remains unclear what action he could take.
In a "60 Minutes" interview that aired on Sunday, Trump said there would be consequences if it turned out Saudi Arabia had anything to do with Khashoggi's mysterious disappearance.