President Donald Trump acknowledged Thursday it “certainly looks” as though missing Saudi journalist Jamal Khashoggi is dead, and he threatened “very severe” consequences if the Saudis are found to have murdered him. His warning came as the administration toughened its response to a disappearance that has sparked global outrage.

Before Trump spoke, the administration announced that Treasury Secretary Steven Mnuchin had pulled out of a major upcoming Saudi investment conference and a U.S. official said Secretary of State Mike Pompeo had warned the Saudi crown prince that his credibility as a future leader is at stake.

Turkish reports say Khashoggi, who had written columns critical of the Saudi government for The Washington Post over the past year while he lived in self-imposed exile in the U.S., was killed and dismembered inside the Saudi Consulate in Istanbul by members of an assassination squad with ties to Saudi Crown Prince Mohammed bin Salman. The Saudis have dismissed those reports as baseless but have yet to explain what happened to the writer.