When asked about Khashoggi's disappearance last Thursday, Trump said that while "we don't like it even a little bit", it wouldn't be "acceptable" to him to stop selling billions of dollars worth of weapons to Riyadh.
Khashoggi, a Washington Post columnist, visited the Saudi consulate in Istanbul on October 2 to obtain papers that would have allowed him to marry his Turkish fiancée.
Attiah told CNN's Anderson Cooper that the explosion of the story provoked her and the Washington Post to publish the column to remind people of Khashoggi's ideas and vision for the Arab world.
"The [Washington] Post held off publishing it because we hoped Jamal would come back to us so that he and I could edit it together".
Crime scene investigators concluded a second search of the consulate and the consul's residence overnight Thursday.
Turkish officials have alleged Kashoggi was killed inside the consulate by Saudi Arabian officials.
Worldwide pressure has also been mounting on Riyadh with United Nations human rights chief Michelle Bachelet calling for the lifting of the immunity of officials who might be involved in Khashoggi's disappearance.
The US president has been on the defensive ever since Khashoggi - a US resident and Washington Post contributor who had criticised Prince Mohammed - vanished on Oct 2 after visiting the Istanbul consulate. "As a result, Arab governments have been given free rein to continue silencing the media at an increasing rate", he wrote.
Prince Mohammed has painted himself as the face of a new, vibrant Saudi Arabia, diversifying its economy away from reliance on oil and making some social changes.
Khashoggi disappeared after entering the Saudi Consulate in Istanbul in early October.
Saudi officials have denied the allegations but it has done nothing to prevent the growing backlash against the regime across the world.
Khashoggi provided examples of crackdowns on the free press in the Arab world, actions he said prevent citizens from knowing the true facts and coming to their own conclusions on issues.
He said: 'The idea that we can treat Saudi as a normal state if it practises state-sponsored murder outside its borders is simply not true'.
Turkish authorities say Khashoggi was killed. "I don't want to get into his mind, but it sounded to me like maybe these could have been rogue killers". "But as to whether or not we should stop $110 billion from being spent in this country, knowing they have four or five alternatives, two very good alternatives, that would not be acceptable to me", the president said, referring to an arms deal that experts have called hugely exaggerated.
The New York Times had reported that Mutreb had travelled extensively with the Crown Prince, perhaps as a bodyguard.
Meanwhile, International Monetary Fund chief Christine Lagarde has become the latest high-profile figure to withdraw from a major Saudi investment conference next week following Mr Khashoggi's disappearance.