Increasing pressure on Trump to respond, a bipartisan group of US senators on Wednesday triggered a USA investigation into Khashoggi's disappearance using a human rights law.
Turkey's Sabah newspaper reports that it has identified 15 members of an intelligence team it says was involved in the Saudi's disappearance.
Saudi officials have strongly denied any involvement in his disappearance and say he left the consulate soon after arriving last Tuesday.
MSNBC host Chris Hayes suggested on Wednesday that President Donald Trump was being secretly bribed by Saudi Arabia in exchange for allowing them to get away with murdering their critics.
Self-exiled Saudi dissident Jamal Khashoggi said earlier this year that the Saudi government has been moving toward nationalist radicalism. "We're probably getting closer than you might think but I have to find out what happened". "We can not let this happen, to reporters, to anybody". Trying to stay calm, I immediately called Yasin Aktay, an adviser to Turkish President Recep Tayyip Erdogan and one of Jamal's oldest friends. "We can not let this happen, to reporters, to anybody".
The Post, citing anonymous United States officials familiar with the intelligence, said Saudi Crown Prince Mohammed bin Salman ordered an operation to lure Khashoggi from his home in Virginia to Saudi Arabia and then detain him.More news: DUP’s Foster challenges May with 'blood red lines' over new Brexit ‘backstop’
With every day, leaks from the Turkish investigation are drip-fed to the media here - and hope that Jamal Khashoggi might still be alive fades further.
Bob Corker, who as chairman of the Senate Foreign Relations Committee has reviewed USA intelligence on the case, said it was likely that Khashoggi was killed the day he walked into the consulate.
Trump told reporters at the White House that he talked with the kingdom's leaders "more than once" since Khashoggi, a U.S. resident and Washington Post contributor, disappeared on Tuesday after entering the Saudi consulate in Istanbul.
The Trump administration has been criticized for not taking a firmer stance against Saudi Arabia and its leader, Crown Prince Mohammed bin Salman, who has vigorously campaigned to convince other nations of its progressive reforms. Local media claim the men are part of a 15-strong hit squad, sent by Saudi Arabia, which includes special forces officers, intelligence officials and a forensics expert.
Secretary of State Mike Pompeo then had a follow-up call with the crown prince to reiterate the US request for information and a thorough, transparent investigation. He says such a move "would be hurting us".
"I also urge Saudi Arabia, especially King Salman and Crown Prince Mohammed bin Salman, to show the same level of sensitivity and release CCTV footage from the consulate", Cengiz wrote. "Maybe we'll be pleasantly surprised, but somehow I doubt it". "I mean, there's no question about it", Corker said, The Hill reported.
The kingdom calls the allegation "baseless", but has not offered any evidence to explain why Mr Khashoggi simply walked out of the consulate and disappeared though his fiancée waited outside for him.
Corker described his talks with Khalid bin Salman, the Saudi ambassador to the USA, as "not a great conversation", and asked to show him video footage of him leaving the consulate.