The disappearance of journalist Jamal Khashoggi on Wednesday prompted senators to initiate an investigation and possible sanctions against Saudi Arabia.
Foreign Relations Committee Chairman Sen. Bob Corker, R-Tenn. and top Democrat Bob Menendez of N.J. issued a letter to President Trump, triggering a probe Wednesday under the Global Magnitsky Human Rights Accountability Act.
The Magnitsky Act requires Trump to determine whether a foreign person is responsible for an extrajudicial killing, torture or other gross violation of internationally recognized human rights. He must then report to the Senate within 120 days with a determination and a decision on the imposition of sanctions.
The letter was signed by 22 Republican and Democratic senators.
Khashoggi, 59, was last seen entering the Saudi Consulate in Istanbul through the main entrance on Oct. 2. Saudi officials insisted, albeit without corroborating evidence, that the columnist for The Washington Post left the building through another exit.
Turkish authorities said Khashoggi was killed by an elite "assassination squad." Saudi Arabia has strongly denied any involvement.
Graham, one of the senators who signed the letter, told Fox News' Martha MacCallum on "The Story" Wednesday night that he spoke with the Saudi ambassador, but noted it was an "unproductive" call.
"It's pretty clear to me that something very bad happened to this man," he said. "If this happened, if they murdered this journalist who works for The Washington Post in a consulate in Istanbul, Turkey — that’s a game changer for me. ... If they did this, there’ll be hell to pay."
Trump said he's spoken to Saudi officials about what he called a "bad situation," and noted the U.S. was working "very closely" with Turkey and that he thinks "we'll get to the bottom of it."
Fox News' Gregory Re and Samuel Chamberlain and The Associated Press contributed to this report.