It seems nearly certain now that Jamal Khashoggi, the Saudi journalist, died a slow and agonizing death, the kind that none of us could dare imagine for ourselves. It seems equally clear that Khashoggi, a Virginia resident and a columnist for the Washington Post, was murdered, probably on orders of the Saudi crown prince, Mohammed bin Salman. The latest evidence pointing to M.B.S.’s direct involvement is the identities of members of the team sent to Istanbul to kill Khashoggi: several of the individuals identified by Turkish officials were part of the Royal Guard, responsible for protecting senior members of the House of Saud. “They answer directly to M.B.S.,’’ Bruce Riedel, a former Middle East specialist for the C.I.A. and National Security Council, told me.

Khashoggi was warm, generous, and funny—and loyal to his principles, like the virtues of open and accountable government. His refusal to compromise his values prompted the Saudi government, in 2016, to silence him, and it led him to conclude, the following year, that he needed to flee to America. I saw Jamal whenever I visited Washington. (Whenever he came to New York, we met at Katz’s Deli for giant reuben sandwiches.) Jamal and I spoke for the last time six days before he vanished. He was writing to tell me about the latest crackdown on the Saudi press, which had led to several reporters being imprisoned. He sent me clips from Saudi newspapers documenting their detention. “I hope you are interested in the story,” Jamal wrote in an e-mail. “Saudi authorities are making a mockery of justice while the world celebrates MBS’ reforms!”

Indeed, if there is any lesson to be learned from this terrible affair, it’s how blind so much of official Washington and the American press were to M.B.S.’s true nature. When the crown prince visited the United States earlier this year, he was fêted in Hollywood and Silicon Valley, on Wall Street, and, of course, by the Trump White House, as a messiah—in the mold of Gorbachev or Gandhi. “Historic night it was,’’ Dwayne (the Rock) Johnson, the actor, wrote, on Instagram, of a dinner with M.B.S. hosted by Rupert Murdoch at his vineyard in Bel Air.

It was the Trump White House that went the furthest, basing its entire Middle East strategy on the vision and maturity of the thirty-three-year-old monarch. As I detailed in my profile of M.B.S., earlier this year, Jared Kushner, sitting down with aides in the White House, unfurled a map of the Middle East shortly after Inauguration Day and wrung his hands at the dire state of the region. He dubbed M.B.S., still the deputy crown prince at the time, “the change agent,” the man who would save Saudi Arabia from otherwise certain doom. Kushner threw the Administration’s support behind him. Not long after, and not least because of the White House’s boost, M.B.S.’s chief rivals, including his cousin, the crown prince, Mohammed bin Nayef, were dispatched. It was ugly, but no one seemed to mind. President Trump’s visit to the Saudi kingdom—his first trip abroad—was an orgy of mutual admiration and monarchical excess.

The truth is that M.B.S.’s violent, impulsive character was visible early on. First came the tale, told to me by a confidant of the crown prince, of a young M.B.S. trying to force a land-registry official to help him seize a parcel of property. When the official balked, M.B.S. sent a single bullet in an envelope to help change his mind. On the Saudi streets, M.B.S. became known as Abu Rasasa, or “father of the bullet.”

Then, in December, 2017, Saad Hariri, the Prime Minister of Lebanon, was detained in Saudi Arabia and held for eleven hours, according to two former American officials active in the region. “The Saudis put him in a chair, and they slapped him repeatedly,” one of the officials told me. (A spokesperson for Hariri denied that he had been beaten.) M.B.S. was angry at Hariri’s allegedly soft treatment of Hezbollah, the Lebanese armed group, but the strong-arm tactics backfired so spectacularly that Hariri returned to his country as a hero. That same year, M.B.S. and his fellow-like-minded monarch, Mohammed bin Zayed, the crown prince of Abu Dhabi, of the United Arab Emirates, announced a blockade of Qatar, a tiny Gulf state, with the hope of overthrowing its king. The scheme fell apart when American officials forcibly intervened.

Then there was the M.B.S.-led military intervention in Yemen, ostensibly waged by Saudi Arabia and the U.A.E. against their Iranian rivals. Since 2016, the campaign has consisted mainly of indiscriminate bombing with American weapons. The toll so far: at least sixteen thousand civilians killed, widespread famine, and a plague of cholera.

The most widely publicized display of M.B.S.’s autocratic streak came in November, 2017, when M.B.S. ordered the roundup of as many as five hundred members of the Saudi royal family. Imprisoned in a five-star hotel, princes and other royals were held captive until they signed over substantial shares of their fortunes. Among those detained was Prince Al-Waleed bin Talal, whose holding company owns large shares of many American companies, including Twenty-First Century Fox. No doubt some of those fortunes were obtained unethically, but M.B.S. afforded the accused no due process, no lawyers, no trials. I heard credible reports that at least some of the men held in the Ritz-Carlton were tortured.

M.B.S. told his countrymen that, in cracking down on corruption, he was doing the dirty work on their behalf. But there was no luxury that he denied himself. In 2015, while vacationing in the South of France, he bought a yacht, the Serene, from a Russian vodka tycoon, for five hundred and fifty million dollars. He bought a château west of Paris, with a cinema and a moat with a submerged glass chamber for viewing carp. And, in 2017, he reportedly spent four hundred and fifty million dollars on “Salvator Mundi,’’ the Leonardo da Vinci portrait of Jesus Christ, which he donated to the new branch of the Louvre in Abu Dhabi, the fiefdom of his fellow-prince M.B.Z.

Unquestioned, and even fawned over, by many in the American government and press, M.B.S.’s self-regard swelled to such proportions that he would no longer subject himself to adult examination. When I asked to interview M.B.S. earlier this year, I was refused. Then, when The New Yorker’s fact checkers sent the Embassy a list of questions, M.B.S.’s minions reacted angrily to inquiries like the one about the bullet story. My questions, Prince Faisal bin Farhan, an Embassy spokesman, told me, were “very disappointing and certainly justified our instinct not to grant any further access.”

Which brings us to now. In apparently ordering the grisly killing of a Washington Post columnist, M.B.S. wagered that the world would not miss another murdered journalist. So far, he has been spectacularly wrong, and the slow drip of information during the past two weeks—from the Turkish government and American officials—has rendered the denials of M.B.S. and other Saudis preposterous. The latest tale, regurgitated by President Trump—that Khashoggi was killed by government “rogues”—is belied by the evidence: among the fifteen members of the hit team that went to meet Khashoggi in Istanbul was a pathologist with a bone saw.

The question now confronting Saudi leaders—and American ones—is whether M.B.S. can and should become king. At a glance, it seems unlikely that King Salman would part with M.B.S., long his favorite son. The humiliation for the House of Saud might be too much to endure. Even if Salman were inclined to remove M.B.S. from the line of succession, who could replace him? Nearly all of M.B.S.’s rivals have been imprisoned or humiliated.

Yet the crisis caused by the murder of Jamal Khashoggi has brought Saudi-American relations to their lowest point in more than forty years. No cover story—about “rogues,” or an interrogation gone awry—is going to paper over the terrible fact that Khashoggi disappeared into the hands of a team of Saudi officials armed with a bone saw, and that he has not been seen, living or dead, since he walked through the door of the Saudi consulate in Istanbul. No American who values a free press should forget Khashoggi’s murder—or let Prince Mohammed bin Salman forget it, either.