Officials leave Saudi Arabia consulate in Istanbul, Oct. 7, 2018.
Turkish officials believe Khashoggi, a United States resident whose writings for the Washington Post were often critical of the crown prince, was killed by a team of assassins who arrived in Turkey from Saudi Arabia the same day he vanished.
Trump expressed reservations about withholding arms sales to Saudi Arabia.
Information continues to trickle out through Turkish media about the 15-man Saudi team previously described as an "assassination squad".
The list also includes the name Mohammad Saad al-Zahrani. Yet the Turkish side has released footage of Khashoggi entering the consulate, while the Saudis have so far failed to offer any evidence to back their claim that the journalist exited the building after picking up papers he needed for his forthcoming marriage to a Turkish woman.
The video then cuts away to traffic outside the Saudi Consulate in Istanbul's upscale 4th Levent neighborhood, showing vehicles with green diplomatic license plates.
The Hurriyet newspaper and other media alleged that the consulate's 28 local staff were given the day off because a "diplomats' meeting" would be held there. The reports did not cite a source and there was no official confirmation of the claim. The report states that a team of 15 Saudi flew to Istambul aboard private jets shortly before the incident. According to a statement of core principles, reported by the Daily Beast, the group would aim to provide "a counter narrative in the Arab world and the West to Arab Spring skeptics".
Mr Erdogan was quoted by Turkish media today as telling journalists flying with him back home from a visit to Hungary that "we can not remain silent to such an incident".
Embassies and consulates under the Vienna Convention are technically foreign soil and must be protected by host nations.More news: Kanye West Goes On 10-Minute Rant During White House Visit
More news: Donald Trump Is Rerouting the World's Oil Tankers
More news: Major League Baseball announces start times for Red Sox-Astros ALCS games
A Saudi Arabian flag flies over the Saudi Arabian consulate in Istanbul on October 10.
A government source has told me President Recep Tayyip Erdogan is sounding more cautious than the leaks, because if he were to echo the allegations that Mr Khashoggi was murdered, it would mean kicking out the Saudi ambassador and consul general by now.
Turkey says it will conduct a search of the Istanbul consulate, while Saudi Arabia's foreign ministry said the country was "open to co-operation" and a search of the building could go ahead.
Mr. Trump told reporters earlier on Wednesday that his administration has been in contact with the "highest level" of officials in the Saudi government, and had asked about Khashoggi's disappearance. "We are demanding everything".
Bob Corker (R-Tenn.), Bob Menendez (D-N.J.), Lindsey Graham (R-S.C.), and Patrick Leahy (D-Vt.) sent a letter to Trump demanding that the USA impose sanctions under the Global Magnitsky Human Rights Accountability Act on any "foreign person responsible for such a violation related to Mr. Khashoggi".
But in his first extensive remarks about Khashoggi's case, Trump warned it is "a very sad situation". We have a lot of things happening in this country.
"Part of that is what we're doing with our defense systems and everybody's wanting them", he continued. "It's a very serious situation for us".
Corker also said that the administration was not given a heads up about the letter prior to its release to reporters, adding that he was unsure about how Trump might respond given his close relationship with the Saudi crown prince.
Khashoggi, 59, is a longtime leading Saudi journalist and former government advisor who went into exile last year after 33-year-old Prince Mohammed rose to power underneath his father the king.
U.S. officials have not confirmed Turkish claims that Khashoggi, a United States resident and one of the more outspoken critics of the regime of King Salman and his son Prince Mohammed, had been lured to the consulate and murdered by a team of 15 government operatives sent by Riyadh to Istanbul.