Top Senate lawmakers wrote to President Trump Wednesday, calling on him to consider sanctioning Saudi Arabia, including its highest-ranking officials, over missing journalist Jamal Khashoggi, who was a critic of the government and has not been seen since entering the Saudi Arabian consulate in Turkey on Oct. 2.

The letter, sent by Senate Foreign Relations Committee Chairman Bob Corker, R-Tenn., and a group of more than 20 bipartisan lawmakers, requests that Trump “make a determination on the imposition of sanctions … with respect to any foreign person responsible for such a violation related to Mr. Khashoggi.”

Turkish officials said Khashoggi, a Washington Post columnist and critic of the Saudi government, was killed upon the orders of Saudi royalty. Saudi Arabia is a top U.S. ally in the Middle East.

Corker and the lawmakers invoked the Global Magnitsky Human Rights Accountability Act in calling on Trump to act.

“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 states.

The act gives the Foreign Relations chairman and ranking member the power to request a president determine if a a foreigner is responsible for “extrajudicial killings, torture, or other gross violations of internationally recognized human rights violations against individuals who seek to obtain, exercise, defend, or promote human rights and freedoms, including freedom of expression.”

It authorizes the president to impose punitive sanctions, and requires a response to Congress within 120 days about the president’s findings.

In the letter, Corker and the lawmakers told Trump the disappearance of Khashoggi “suggests that he could be a victim of a gross violation of internationally recognized human rights.”