The Wall Street Journal published Trump's remarks hours before Crown Prince Mohammed bin Salman's appearance at a business conference where he is due to make his most high profile comments since Khashoggi was killed on Oct. 2.

An adviser to Turkey's president meanwhile said Prince Mohammed had "blood on his hands" over Khashoggi, the bluntest language yet from someone linked to Tayyip Erdogan about the de facto ruler of the kingdom in connection with the death.

Saudi authorities did not immediately respond to a request for comment about the remarks by Trump and the Erdogan adviser.

Read: Saudi Explanation of Khashoggi Killing Not Enough, US says

Riyadh has blamed a "rogue operation" for the death of the prominent Saudi journalist, a critic of the crown prince, and said the crown prince had no knowledge of the killing.

Trump told the Journal he wanted to believe the prince when he said that lower-level officials were to blame for the killing at the Saudi consulate in Istanbul.

But he suggested responsibility lay higher up: "Well, the prince is running things over there more so at this stage. He's running things and so if anybody were going to be, it would be him."

The death of Khashoggi, a U.S. residentandWashington Post columnist, has sparked global outrage and threatened relations between Riyadh and Washington as well as other Western nations.

For Saudi Arabia’s allies, the burning question has been whether they believe that Prince Mohammed, who has painted himself as a reformer, has any culpability in the killing, a possibility raised by several U.S. lawmakers.

CONFLICTING ACCOUNTS

Saudi Arabia has given conflicting accounts about Khashoggi's killing. It first denied his death and later said Khashoggi - a U.S. resident and columnist for the Washington Post - died inside the consulate after a fight.

On Sunday Riyadh called the killing a "huge and grave mistake," but sought to shield the crown prince from the widening crisis, saying he had not been aware.

Read: Saudi Arabia Admits Khashoggi Died in Consulate

Turkish security sources say that when Khashoggi entered the consulate, he was seized by 15 Saudi intelligence operatives who had flown in on two jets just hours before.

"It is a disgrace that reaches all the way to Crown Prince (Mohammed bin) Salman. At least five members of the execution team are (Mohammed bin) Salman's right hands and are people that wouldn't act without his knowledge," Ilnur Cevik, one of several advisers to Turkey's Erdogan, wrote in the Yeni Birlik newspaper.

"Even if U.S. President Trump saves (Mohammed bin) Salman, in the eyes of the world he is a questionable person with Khashoggi's blood on his hands," Cevik's column said.

It was not immediately clear whether the Cevik's reflected the views of Erdogan, who in speeches on Tuesday and Wednesday highlighted the need for all of those responsible - "from those who ordered it to those who carried it out" - to face justice.

Saudi Arabia has agreed to conduct a joint investigation into Khashoggi's killing with the Turkish authorities, with its consulate in Istanbul searched days after the journalist's death.

As part of that probe, Turkish police in Istanbul have been granted permission to search a well in the garden of the Saudi consulate, broadcaster NTV said, after Saudi officials had earlier refused to allow a search.

REUTERS