Two days after Donald Trump’s election, Jamal Khashoggi returned to the Red Sea port city of Jeddah from Washington where he’d given a foreign-policy talk lightly critical of then president-elect Trump, when he received a phone call from the media adviser to the kingdom’s ascendent deputy Crown Prince Mohammed bin Salman, better known by his initials M.B.S. “He said, ‘You’re not allowed to tweet or write your column or give comments to foreign journalists,’” Khashoggi recalled to me in March 2018. “I was ordered silent.”

As a member of the Saudi elite for decades, Khashoggi understood that political expression had strict limits in the kingdom, but M.B.S.’s apparent determination to quell even mild dissent on foreign soil left Khashoggi unnerved. Ten months later, in September 2017, he fled to Washington. “I began to feel whatever narrow space I had in Saudi Arabia was getting narrower. I thought it would be better to get out and be safe,” he told me.

I initially contacted Khashoggi for a prospective article about the young prince’s relationship to the White House, which I shelved because he was one of the few people who would speak openly. When he left Saudi Arabia, Khashoggi told me, he didn’t see himself in the mold of a dissident. He’d been editor-in-chief of the Saudi newspaper Al Watan and a media adviser to Prince Turki al-Faisal, Saudi Arabia’s ambassador to Britain. Moreover, he wanted M.B.S. to succeed. “He truly wants to make Saudi Arabia great again. But he is doing it the wrong way,” Khashoggi told me.

But a month after his departure from the kingdom, Khashoggi’s view of M.B.S. fundamentally changed. Saudi security services arrested scores of prominent businessmen and imprisoned them inside the Ritz-Carlton under the guise of an “anti-corruption” crackdown. Khashoggi soon began hearing from friends in Saudi Arabia that prisoners were coerced, in some cases tortured, into turning over billions of dollars to the government. “It was tough. Some were insulted. Some were hit. Some claim they were electrocuted,” he said. The purge, which also included intellectuals, media personalities, and moderate clerics, convinced Khashoggi that M.B.S. had sold himself as a reformer when in fact he was a brutal authoritarian. “When the arrests started happening, I flipped. I decided it was time to speak,” he told me.

Khashoggi subsequently landed a column in The Washington Post where he wrote critically about M.B.S.’s internal power grab; his reckless military intervention in neighboring Yemen, where he has created a humanitarian emergency; and the prince’s bizarre plot to kidnap Lebanese prime minister Saad Hariri. “Saudi Arabia wasn’t a free society, but people weren’t being arrested like this,” he said. “The people M.B.S. arrested were not radicals. The majority were reformers for women’s rights and open society. He arrested them to spread fear. He is replacing religious intolerance with political closure.” An adviser to one prominent Saudi businessman who was arrested told me: “People are scared. It has become a bit of a police state.”

Tragically, Khashoggi’s self-imposed exile didn’t keep him safe. Earlier this month, Khashoggi entered Saudi Arabia’s consulate in Istanbul to obtain documents he needed for his upcoming wedding and never emerged. Turkish officials have told Western journalists that a kill team of 15 Saudi agents detained Khashoggi inside the consulate, tortured him to death, and dismembered his body with a bone saw. M.B.S. and his father, King Salman, have denied their involvement in Khashoggi’s disappearance, but already the grisly episode has damaged M.B.S.’s ambitions to cultivate global elites. A parade of C.E.O.s including Uber’s Dara Khosrowshahi, JPMorgan Chase’s Jamie Dimon, and BlackRock’s Larry Fink have canceled plans to attend an investment conference hosted by M.B.S. next week at the Riyadh Ritz-Carlton dubbed “Davos in the Desert,” though Fink, at least, has said he’ll maintain his business ties to the kingdom.