A bipartisan group of senators wrote to the White House on Wednesday invoking the Global Magnitsky Human Rights Accountability Act to demand an investigation into the disappearance of journalist Jamal Khashoggi and possible sanctions against Saudi Arabia.

One of the co-authors of the letter, Senator Bob Corker (R-TN), said he has seen intelligence reports indicating Saudi Crown Prince Mohammed bin Salman ordered an operation to lure Khashoggi to Saudi Arabia so he could be arrested.

The letter was written by Corker and Senator Bob Menendez (D-NJ) of the Foreign Relations Committee and Senators Lindsey Graham (R-SC) and Patrick Leahy (D-VT) of the Appropriations Subcommittee on State, Foreign Operations, and Related Programs. The 22 signatories included Senators Marco Rubio (R-FL), Chris Murphy (D-CT), Tim Kaine (D-VA), and Ron Johnson.

The letter noted the Magnitsky Act – named for Russian lawyer Sergei Magnitsky, who the Russian government arrested and killed in 2009 after uncovering widespread corruption – requires the president to investigate “extrajudicial killing, torture, or other gross violation of internationally recognized human rights” by foreign authorities upon request by the Senate. The senators indicated there are reasons to believe Khashoggi has suffered such abuse.

“Therefore, we request that you make a determination on the imposition of sanctions pursuant to the Global Magnitsky Human Rights Accountability Act with respect to any foreign person responsible for such a violation related to Mr. Khashoggi. Our expectation is that in making your determination you will consider any relevant information, including with respect to the highest ranking officials in the Government of Saudi Arabia,” the letter stated.

Corker told reporters on Wednesday he appreciates the reform agenda pursued by Saudi Crown Prince Mohammed bin Salman, who is commonly referred to by his initials “MBS,” but made it clear the abduction or murder of Khashoggi was completely unacceptable if the Saudi government was involved.

“MBS is a person of the future. He’s got a vision for the country that I think is extraordinary for a young leader,” Corker said, while making it clear the Crown Prince could nonetheless be targeted personally by U.S. sanctions if he was complicit in Khashoggi’s disappearance.

“We need to push back on activities like this if they have occurred,” Corker said. “We need to nip it in the bud. This is what this is intended to do, to send a strong message from us. It’s my hope that it doesn’t lead to the top. Indications are that if in fact he was murdered, it could well do so.”

The Washington Post on Wednesday reported U.S. intelligence intercepted communications from Saudi officials over the past four months indicating Crown Prince bin Salman ordered an operation to lure Khashoggi to Saudi Arabia so he could be arrested.

“Several of Khashoggi’s friends said that over the past four months, senior Saudi officials close to the crown prince had called Khashoggi to offer him protection, and even a high-level job working for the government if he returned to his home country,” the Post reported.

Khashoggi’s response to these offers, according to one of his friends, was: “Are you kidding? I don’t trust them one bit.”

U.S. officials quoted by the Post described the intelligence concerning a Saudi plot to abduct Khashoggi as too vague to trigger a warning to the journalist under longstanding American policy. The office of the Director of National Intelligence would neither confirm or deny that Khashoggi received a warning. A spokesman for the State Department insisted the U.S. government had “no advance warning” of Khashoggi’s disappearance.

“We can confirm that Ambassador Bolton and Jared Kushner have spoken to the crown prince yesterday, and we can confirm as well that the Secretary of State then had a follow-up call with the crown prince to reiterate our request for more information. We continue to call for a transparent investigation, and we’re going to continue to monitor this situation,” the State Department said on Wednesday.

One former intelligence official speculated the mysterious 15-member team sent from Saudi Arabia to Istanbul on the day of Khashoggi’s disappearance intended to conduct a “rendition” operation and spirit him back to Saudi territory, but something may have gone wrong and resulted in Khashoggi’s death. On the other hand, a “source close to the royal family” told the UK Daily Mail Khashoggi is alive and was successfully transported to Saudi Arabia.

The Washington Post described President Donald Trump as increasingly frustrated with the lack of response from Saudi officials on questions related to the Khashoggi case. The White House is reportedly considering options to “force Saudi Arabia to provide answers” and punish the Saudi government if necessary.

“We cannot let this happen to reporters, to anybody. We’re demanding everything. We want to see what’s going on there,” President Trump said on Wednesday.

Turkish media on Thursday identified more of the 15 members of the Saudi team sent to the Istanbul consulate last Tuesday when Khashoggi disappeared. The team was already known to include a forensic medical expert. According to the new reports, it also included intelligence officers, soldiers, and members of the royal guard. The uniform nature of these reports and their detailed nature suggest the Turkish government is feeding intelligence reports to the media for publication.

Possibly angered by Turkey’s extensive coverage of the team that was sent to the consulate, Saudi authorities abruptly changed their minds about allowing Turkish investigators access to the consulate and blocked the Turks from entering on Wednesday.

The New York Times on Wednesday withdrew as a media sponsor of the upcoming “Davos in the Desert” economic conference, a major event hosted by Saudi Arabia from October 23 to 25. Human rights activists are pressuring other media operations and corporate participants to withdraw from the conference to protest Khashoggi’s disappearance. U.S. Treasury Secretary Steven Mnuchin is currently scheduled to attend the event.