(CNN) -- US Secretary of State Mike Pompeo held talks with top Saudi leaders Tuesday as sources told CNN that the Kingdom is preparing to acknowledge that missing journalist Jamal Khashoggi died at the Saudi consulate in Istanbul, Turkey.
Pompeo had a short discussion with King Salman before a longer meeting with the King's son, Crown Prince Mohammed bin Salman, Saudi Arabia's de facto ruler. US State Department spokeswoman Heather Nauert said Pompeo "thanked the King for his commitment to supporting a thorough, transparent, and timely investigation" of the Khashoggi case and expressed "concern" about the case to the foreign minister.
Nauert described the meetings as "direct and candid."
CNN's sources say Saudi Arabia plans to contend that the Washington Post columnist died when an interrogation went awry, but there was no public mention on Tuesday of any new Saudi explanation of Khashoggi's disappearance.
Turkey's President Recep Tayyip Erdogan said Turkish officials, who searched the consulate for nine hours on Monday, are looking into "toxic" and "painted over material" as part of their investigation. "My hope is that we can reach conclusions that will give us a reasonable opinion as soon as possible, because the investigation is looking into many things such as toxic materials and those materials being removed by painting them over," Erdogan told reporters.
Saudi Arabia has been under intense international pressure to explain Khashoggi's apparent death after he visited the consulate on October 2 to obtain papers that would have allowed him to marry his Turkish fiancée.
The affair has created a diplomatic rift between Saudi Arabia and the West and led to international firms pulling out of a high-profile summit in Riyadh. The CEOs of three top banks -- Standard Chartered, HSBC and Credit Suisse -- announced their withdrawal from the conference Tuesday.
Khashoggi's family called for an independent, international commission to investigate the case.
Flurry of meetings
Trump dispatched Pompeo to the region shortly after a phone call on Monday with King Salman. He was met at the airport in Riyadh on Tuesday by the Saudi foreign minister, and was undertaking a flurry of engagements with top officials throughout the day.
Pompeo's meeting with the King was relatively brief -- based on the arrival and departure times of his motorcade, CNN estimates the encounter can have lasted no more than 15 minutes. Pompeo met with the Crown Prince for about 35 to 40 minutes, and was due to meet him again for dinner later.
Turkish authorities have said privately that Khashoggi was killed at the consulate on October 2. Saudi Arabia has previously insisted he left the building the same afternoon, but have provided no evidence to support the claim. His fiancée, Hatice Cengiz, waited outside the consulate and says she did not see him re-emerge.
Cengiz tweeted a Quranic verse on Tuesday promising "eternal hellfire" for the killers of "deliberate believers."
Turkish investigators will carry out a search of the Saudi Consul General's residence in Istanbul on Tuesday, according to a Turkish diplomatic source. CCTV footage, which has served as a focal point in the investigations, showed vehicles moving from the consulate building to the nearby Consul General's residence on October 2.
Officials, including a forensics team, conducted an investigation of the consulate that lasted well into the evening on Monday. Earlier in the day, CNN reporters saw a cleaning crew enter the building.
United Nations human rights chief Michelle Bachelet called on Riyadh to lift immunity -- bestowed by the Vienna Convention on Consular Relations -- on its diplomatic premises and officials over the case of the disappeared journalist.
"Under international law, both a forced disappearance and an extra-judicial killing are very serious crimes, and immunity should not be used to impede investigations into what happened and who is responsible," Bachelet said in a statement released Tuesday.
"Two weeks is a very long time for the probable scene of a crime not to have been subjected to a full forensic investigation."
Saudis' shifting story
Sources told CNN on Monday that the Saudis are preparing a report that will acknowledge that the death of Khashoggi, a former Saudi royal insider who became a critic of Crown Prince Mohammed bin Salman, was the result of an interrogation that went wrong. The sources said the interrogation was intended to lead to his enforced return to Saudi Arabia.
One source said the report will likely conclude that the operation was carried out without clearance and transparency and that those involved will be held responsible. A source acknowledged that the report was still being prepared and cautioned that things could change.
If Riyadh goes public with its new explanation, it would require a reversal of its previous claim that Khashoggi had left the consulate alive.
After Trump's call with King Salman on Monday, he floated the possibility that Khashoggi died during an unauthorized operation. "It sounded to me like maybe these could have been rogue killers -- who knows," Trump told reporters.
Trump's comments may be a sign that Washington is preparing to accept Saudi Arabia's efforts to distance its leaders from whatever fate befell Khashoggi at its Istanbul consulate.
Late Monday, Khashoggi's family issued a statement in which they acknowledged for the first time that the journalist was no longer alive. "The strong moral and legal responsibility which our father instilled in us obliges us to call for the establishment of an independent and impartial international commission to inquire into the circumstances of his death," they said in the statement.
The tone differed markedly from the statement released by members of the family on October 7, in which they accused the media of politicizing his disappearance and affirmed their trust in the Saudi government to resolve the case.
It was unclear on Tuesday when or if Saudi Arabia would go public with any new admissions in relation to Khashoggi's disappearance. Turkish authorities said they believed that 15 Saudi men who arrived in Istanbul on October 2 were connected to the case. At least some of them appear to have high-level connections in the Saudi government.
If that group is to be characterized as part of a rogue operation intended to bring Khashoggi back to Saudi Arabia alive, questions could arise about Salah Muhammed al-Tubaiqi. He is listed on an official Saudi website as the head of the forensic medicine department at the interior ministry, and who Turkish officials have named as one of the 15-person group.
If the autopsy specialist left Saudi Arabia for Istanbul before Khashoggi entered the consulate, as Turkish sources have asserted, it might be hard to square with the explanation that any killing was the result of a botched interrogation, and not premeditated.
Even if the Trump administration accepts the new Saudi explanation, members of Congress might not. Democratic lawmakers criticized the President for his comments after the call with King Salman.
"Been hearing the ridiculous 'rogue killers' theory was where the Saudis would go with this," Sen. Chris Murphy of Connecticut said on Twitter. "Absolutely extraordinary they were able to enlist the President of the United States as their PR agent to float it," he added.
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