Washington CNN  — 

President Donald Trump on Monday repeatedly highlighted the Saudi King’s denial of involvement in the disappearance of Jamal Khashoggi, at one point offering up an alternative theory that “rogue killers,” rather than agents of the Saudi regime, were involved.

Trump also said he was dispatching Secretary of State Mike Pompeo to meet with King Salman.

“It wasn’t like there was a question in his mind. The denial was very strong,” Trump told reporters outside the White House, adding that the King “firmly denied any knowledge” of what happened to Khashoggi, a Washington Post journalist and Saudi dissident.

The President said he spoke with Salman on the phone Monday, and said that after the call, he believed “rogue killers” may have killed Khashoggi, suggesting that was a possible explanation Salman offered up during their conversation.

“It sounded to me like maybe these could have been rogue killers, who knows. We are going to try to get to the bottom of it very soon,” Trump said. “But his was a flat denial.”

The President said he was simply relaying the Saudi king’s denial and vowed that “we will check it all out.”

Lawmakers who have seen US intelligence reports on Khashoggi’s October 2 disappearance from the Saudi Arabian consulate in Istanbul, however, have said there’s little doubt as to who is responsible.

Senate Foreign Relations Chairman Bob Corker, a Tennessee Republican, told CNN that the “intel points directly” to Saudi Arabia for Khashoggi’s disappearance and said it needs to produce the 59-year-old father of four to dispel concerns.

Turkish authorities believe 15 Saudi men who arrived in Istanbul on private planes on October 2 were connected to the disappearance – and that they have high-level connections to the Saudi government. A Saudi source familiar with four of the 15 men who are persons of interest in the case tells CNN that one of the men is a former diplomat in London and an intelligence officer, and another of the men is a forensics expert.

The President said Monday that Pompeo will “immediately get on a plane” to Saudi Arabia and will likely also go to Turkey “if necessary” to look into the matter.

Trump also emphasized the joint investigation between Turkey and Saudi Arabia, saying King Salman told him “Turkey and Saudi Arabia are working hand in hand, very closely, on getting to the bottom of what happened.”

The President has been reluctant to castigate Saudi Arabia, a key US ally which plays a central role in the Trump administration’s Middle East policy, despite growing pressure from congressional Republicans. In a “60 Minutes” interview that aired Sunday, the President said that there would be “severe punishment” if Khashoggi were found to have been killed, but has not publicly shared any details about any possible investigations into Khashoggi’s disappearance.

International pressure also is mounting on Riyadh to explain the journalist’s disappearance. Saudi Arabia has given Turkey permission to search its Istanbul consulate Monday afternoon, a Turkish diplomatic source told CNN.

Khashoggi, a former Saudi royal insider who became a critic of the country’s government, disappeared almost two weeks ago after he went into the Saudi Arabian consulate in Istanbul, Turkey, to obtain paperwork to marry his Turkish fiancée.

CNN’s Allie Malloy contributed to this report.