(CNN) President Donald Trump will meet Secretary of State Mike Pompeo on Thursday as the White House struggles to contain a spiraling crisis over a journalist's apparent death at a Saudi consulate.

Trump stressed Wednesday that he does not want to abandon Riyadh as it comes under increasing pressure to explain the disappearance of Washington Post columnist Jamal Khashoggi , who has not been seen since entering the consulate in Istanbul, Turkey, on October 2.

Trump denied that he was "giving cover" to Saudi Arabia, insisting that he wants to get to the bottom of what happened.

"I want to find out what happened, where is the fault, and we will probably know that by the end of the week. But Mike Pompeo is coming back, we're gonna have a long talk," he said.

Pompeo, who returned to Washington on Wednesday after an emergency diplomatic mission to meet Saudi and Turkish leaders, has also faced criticism that the US was giving the Saudis "the benefit of the doubt."

US Secretary of State Mike Pompeo meets with Saudi Crown Prince Mohammed bin Salman in Riyadh on Tuesday.

But Trump again emphasized the importance of Washington's relationship with Saudi Arabia, pointing to Saudi investments in the US.

"They're a tremendous purchaser of not only military equipment, but other things," Trump told reporters Wednesday.

Trump's loyalty to Riyadh has become increasingly difficult to defend as allegations are mounting that Khashoggi's possible death may be connected to people close to the highest levels of the Saudi government. Turkish authorities believe that 15 Saudi men who arrived in Istanbul on October 2 were connected to Khashoggi's likely death. At least some of them appear to have high-level connections in the Saudi government.

Sources told CNN that the Saudi group was led by a high-ranking intelligence officer, with one source saying he was close to the inner circle of the kingdom's Crown Prince Mohammed bin Salman.

Several officials have told CNN that any killing could not have happened without the direct knowledge of the 33-year-old crown prince, who is known by his initials "MBS."

Grisly details from an audio recording Turkey claims to have from within the Saudi consulate suggest that Khashoggi was tortured then killed soon after entering the consulate, according to Turkish media. Turkish officials have told CNN that Khashoggi's body was then dismembered.

Khashoggi may have been injected with some kind of tranquilizer before his death, a source told CNN.

On Tuesday, the same day Pompeo landed in Riyadh, $100 million from the Saudi government arrived in Washington for US efforts to stabilize Syria, according to a State Department official.

This contribution follows the request from President Trump for partners to share the burden of promoting stability in Syria, but its timing raised questions about a potential sop as Riyadh seeks to limit damage over allegations over Khashoggi's disappearance.

The State Department denied any connection between the payment and the Khashoggi crisis.

"We always expected the contribution to be finalized in the fall time frame," Brett McGurk, a State Department officials, said in a statement. "The specific transfer of funds has been long in process and has nothing to do with other events or the secretary's visit."

'Total denial'

The crisis has led to a diplomatic imbroglio entangling Washington, Riyadh and Istanbul and prompted criticism of Trump's seeming reluctance to pressure the kingdom over the allegations.

Bipartisan groups of US lawmakers have begun to back international demands for an independent investigation into Khashoggi's disappearance and are calling on Trump, who has touted the crown prince's "total denial" of any involvement, to reveal his personal financial ties to Saudi Arabia. The G7 foreign ministers on Tuesday called for those responsible to be held accountable.

Khashoggi's disappearance has also led to international firms pulling out of a high-profile summit in Riyadh this month. The CEOs of three top banks announced their withdrawal from the conference Tuesday. International Monetary Fund chief Christine Lagarde has also canceled her attendance.

Throughout, the US administration has continued to defend Riyadh. Trump said Wednesday that the US has asked Turkey for a copy of an audio recording that may have captured the death and dismemberment, while seeming to cast doubt on whether the recording even exists.

Turkish police officers gather outside the Saudi consul general's residence in Istanbul Wednesday.

"We have asked for it, if it exists," Trump said. "I'm not sure yet that it exists. Probably does. Possibly does."

Asked if the Saudi officials told him whether Khashoggi was dead or alive, Pompeo said: "I don't want to talk about any of the facts. They didn't want to either. They want to have the opportunity to complete this investigation in a thorough way... I think that's a reasonable thing to do, to give them that opportunity and then we'll all get to judge."

However, a source told CNN that Pompeo privately warned the crown prince in no uncertain terms that he had to "own" the situation, and "that every fact is going to get out," according to the source.

Speaking to reporters in Brussels about Saudi pledges to investigate what has happened, Pompeo conceded that there "had been a couple of delays" in the Saudi preparation of a report, but said that it was "reasonable to give them a handful of days more to complete" their own investigation "so they get it right, so that it's thorough and complete."

He added, "sooner is better than later."

Saudi intelligence led operation

Saudi officials had previously maintained Khashoggi left the consulate the same afternoon of his visit, but they provided no evidence to support the claim.

Sources have told CNN that the kingdom was preparing a report to acknowledge that Khashoggi died at the consulate in an interrogation that went awry. 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.

But a Saudi admission that Khashoggi died in the consulate would not deter difficult questions over the whereabouts of his remains, or the movements of the 15 men and their links to bin Salman.

The high-ranking officer who led the group of men to Istanbul came from the General Intelligence Presidency, the main Saudi intelligence service, three sources familiar with the case told CNN.

One of the men under investigation by Turkish authorities is Maher Abdulaziz Mutreb, a Saudi diplomat and intelligence officer. Mutreb is closely connected to bin Salman, a Saudi source told CNN.

"He was seconded to an elite protection brigade within the Royal Guard to serve as the personal security force of (the Crown Prince)," the source told CNN.

Photographs have emerged of Mutreb with bin Salman during the Crown Prince's tour of the United States earlier this year. Mutreb was the first secretary at the Saudi embassy in London, according to a 2007 UK government list of foreign diplomats and a Saudi source in London who knew him and described him as a colonel in Saudi intelligence.

Turkish officials also provided CNN with passport scans of seven other men they suspect to have been part of the Saudi team. The passport scans were taken on the day of Khashoggi's disappearance.

One of the passport scans appears to belong to Salah Muhammad al-Tubaiqi, listed as the head of forensic medicine at the Saudi Ministry of Interior.

In a 2014 interview with Asharq al-Awsat, a London-based Saudi newspaper, Tubaiqi lauded a mobile clinic designed to carry out autopsies in a record seven minutes as the first of its kind in the world. Tubaiqi, who was working as the forensic consultant and supervisor of the clinic at the time, told the newspaper it was his idea to design the clinic to allow coroners to perform forensic examinations and dissect bodies at crime and accident scenes.

Another member of the group identified by Turkish official media and appearing in the alleged passport scans is Muhammad Saad al-Zahrani, who has appeared on Saudi state TV alongside Saudi Crown Prince Mohammed bin Salman.

If that group is to be characterized by Saudi Arabia as part of a rogue operation intended to bring Khashoggi back to the kingdom alive, it still might be difficult to explain how a group of men so close to the heart of the Saudi establishment operated without the crown prince's knowledge.

Turkish officials on Tuesday provided CNN with passport scans of Muhammad Saad al-Zahrani, left, and Salah Muhammad al-Tubaiqi.

If Turkish officials' allegations were proven that Khashoggi was murdered soon after entering the consulate that would contradict the idea that he died as a result of a botched interrogation.

Another line of questioning might focus on al-Tubaiqi. For example, 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 not premeditated.

Questions have also been raised by Turkish authorities over Saudi Arabia's lack of cooperation in investigating the disappearance.

By the time Turkish investigators gained access to the consulate Monday evening, a fresh coat of paint had been applied "everywhere" inside the building, a Turkish official told CNN Tuesday. The source demanded that Saudi Arabia make "a genuine contribution" to the investigation.

Turkish investigators searched the Saudi consul general's residence in Istanbul on Wednesday. The search at the residence, which also involved dogs, went into the early morning hours Thursday. It was unclear if anything was discovered.

The Saudi consul general, Mohammad al-Otaibi, left the country on Tuesday, Turkish state news agency Anadolu reported.