Donald Trump has compared Saudi Arabia being accused of murdering journalist Jamal Khashoggi to Brett Kavanaugh being accused of sexual assault.
The US president criticised the rapidly mounting global condemnation of the kingdom for allegedly murdering the journalist, a US citizen, in its Istanbul consulate.
"I think we have to find out what happened first," he said. "Here we go again with, you know, you're guilty until proven innocent. I don't like that.
"We just went through that with Justice Kavanaugh and he was innocent all the way as far as I'm concerned."
Mr Kavanaugh was sworn in as a US Supreme Court judge on 6 October after denying allegations that he assaulted Dr Christine Blasey Ford when they were at high school together.
Mr Trump's remarks are his most robust defence yet of the Saudis, a US ally he has made central to his Middle East agenda.
But they put the president at odds with other key allies, including the UK, Germany, France and fellow Republicans.
The International Monetary Fund's (IMF) managing director Christine Lagarde said on Wednesday morning she is deferring a scheduled trip to the Middle East in which she was meant to be attending an important investment conference in Riyadh.
The president's comments came a day after he spoke on the phone to Crown Prince Mohammed bin Salman, who he said "totally denied any knowledge of what took place in their Turkish consulate".
On Tuesday, Saudi's consul general, Mohammed al-Otaibi, reportedly left Turkey hours after it was announced his official residence would be searched in connection with the journalist's disappearance.
Police searched the nearby Saudi consulate and said they found evidence dissident writer Mr Khashoggi died there, a senior Turkish official said.
Saudi Mr Khashoggi, 60, has not been seen since entering the building on 2 October to get documents for his wedding.
Turkish President Tayyip Erdogan has suggested parts of the consulate had been repainted since the disappearance of the journalist, who was a critic of the Saudi regime.
Mr Erdogan said: "The investigation is looking into many things such as toxic materials and those materials being removed by painting them over."
There are claims that Mr Khashoggi was killed and dismembered inside the building by a 15-member Saudi "assassination squad".
Saudi Arabia previously called the allegation "baseless", but reports suggest they may admit he died during a botched interrogation.
Mr Trump sent his top diplomat, secretary of state Mike Pompeo, to Riyadh to discuss the incident with King Salman and Crown Prince Mohammed bin Salman.
Mr Pompeo, who met the pair on Wednesday morning, told journalists before leaving Riyadh that they "made a commitment to hold anyone connected to any wrongdoing that may be found accountable for that, whether they are a senior officer or official."
The crown 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," the president said in a tweet.
Until Monday, Riyadh had not allowed Turkish investigators to search the consulate, with reports both sides were at odds over the conditions.
The investigators, who eventually searched the premises for eight hours, took samples with them, including soil from the consulate garden, according to an official at the scene.
Forensic vehicles also took away a metal door from the garden.
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Mr Khashoggi appeared regularly on Arab talk shows and moved to Washington last year.
He had been critical of Prince Mohammed, who has cracked down on dissent with arrests.