Speaking on Tuesday at the Oval Office, the U.S. leader criticised the country's long-term ally for one of the "worst cover-ups in the history of cover-ups".
"Bad deal, should have never been thought of. Somebody really messed up", he said.
Trump had previously suggested that the Saudi explanation for Khashoggi's death was credible.
Khashoggi Death: Turkish President Says Saudis Killed Journalist In A 'Savage Way'
Mr Khashoggi was a known critic of the Saudi government and the country's crown prince, Mohammed bin Salman.
When asked whether the USA would accept Saudi Crown Prince Mohammed bin Salman's explanation of the incident, Mr Pompeo said: "We're going to accept what America learns". Erdogan has said that he would share the information of the investigation in a speech on Tuesday.
Erdogan also called on Saudi King Salman "to do what it takes because the crime has taken place in Istanbul and we need to know".
Several countries, including Germany, Britain, France and Turkey, have pressed Riyadh to provide all the facts, and Chancellor Angela Merkel said Berlin would not export arms to Saudi Arabia while uncertainty over Khashoggi's fate persisted.
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In a statement Sunday, the governments said attacks on journalists were unacceptable and "of utmost concern to our three nations". The official said Saudi statements had changed because of "false information reported internally at the time".
"But we'll also do so in the context of our vital national interests and the important and more than half-century long relationship between the United States and Saudi Arabia", Pence said.
Jeremy Hunt, the foreign secretary said he was "deeply concerned to hear President Erdogan describe Jamal Khashoggi's murder as pre-meditated".
Gina Haspel, the then-nominee for the CIA Director post, testifies at her confirmation hearing before the Senate Intelligence Committee on Capitol Hill in Washington, US, May 9, 2018.
Since Saudi accounts said a "local collaborator" had disposed of Khashoggi's remains, Erdogan said, "I am now asking: Who is this local collaborator?"
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Anderson said new Australia captain Tim Paine was "a genuinely nice guy" and was also complimentary about other team members. Marnus Labuschagne has been superseded as the dumbest batsman", the former Australian skipper said.
Erdogan further mentioned that out of the 18 Saudi nationals arrested, 15 were the very same Saudis who have been identified by Turkish authorities who arrived in Istanbul before the incident that left Khashoggi dead.
Riyadh says Khashoggi was accidentally choked during a rendition attempt that went wrong, and his body was rolled up in a rug and given to a third party. "This kind of brutality is against the collective human conscience".
Saudi Ambassador to the U.S. Prince Khalid bin Salman, a brother of the crown prince, wrote October 8 that Khashoggi had left, and that claims the kingdom "have detained him or killed him are absolutely false, and baseless".
He also said that cameras at the consulate had been removed the day before the team's arrival.
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The Telegram channel 112 identified the man as Vladislav Roslyakov, an 18-year-old fourth-year student of the polytechnic college. Kerch is the landing point and namesake of a bridge that opened earlier this year to connect Crimea to Russian Federation .
Erdogan did not blame Crown Prince Mohammed by name in his speech. "Why is the body of a person who has officially been accepted as killed still not around?"