Trump tweeted after a phone call with the prince. Trump said the Saudi heir "totally denied any knowledge of what took place in their Turkish Consulate." He added that the prince "told me that he has already started, and will rapidly expand, a full and complete investigation into this matter. Answers will be forthcoming shortly."
Within days of Khashoggi's disappearance, Turkish investigators said they had pieced together most of the mystery, concluding that he had been killed inside the consulate and dismembered.
Turkey said a 15-member team dispatched from Saudi Arabia played a role in the killing. Turkish officials have confirmed that the 15 names reported in the Turkish media are those of the suspected team members, and their alleged involvement is part of the evidence cited by Turkey that Saudi Arabia was responsible for Khashoggi's death.
Saudi officials have repeatedly denied any involvement in Khashoggi's disappearance and say they have no information about his whereabouts.
Over the past two days, Saudi Arabia has allowed Turkish police to search the consulate. But investigators have been frustrated with what they say is a lack of Saudi cooperation, according to two senior Turkish officials, who cited the long delay before they were allowed to enter the consulate.
They also noted apparent Saudi attempts to scrub the scene by bringing in cleaning crews and repainting areas of the consulate. "People who have nothing to hide," one official said, "don't behave like this."
Saudi Arabia has made no official statement about the men or said why they may have been in Istanbul on October 2. A report on the Saudi-owned al-Arabiya news channel said the 15 were "tourists" who had been falsely accused.
The senior Turkish officials, who spoke on the condition of anonymity, said they were eager to interview members of the 15-man Saudi team, all of whom were believed to have arrived and left Istanbul on the day Khashoggi disappeared. It was not clear why Turkish officials did not provide scans of all 15 passports.
The UN special investigator on torture says if Turkey and Saudi Arabia can't conduct "a credible and objective investigation" into the disappearance of Saudi journalist Jamal Khashoggi then there may be a need for international involvement.
Nils Melzer told a news conference at UN headquarters in New York that "we should give the involved states time, and under proper scrutiny, to come to a conclusion that they want to address this problem."
But Melzer said if at a later stage "we can see that one of the involved states does not fulfill its international obligations in regard to being cooperative in investigating this case, then obviously it might be an occasion where I could intervene also publicly and call on the involved states to fulfill their obligations."
- additional reporting AP
