After a month, it seems we finally have a good picture of Jamal Khashoggi’s last moments. In early October, the Saudi journalist and Washington Post columnist entered the Saudi consulate in Istanbul and was immediately descended upon by members of the Saudi government hit squad sent to kill him. They strangled him to death, according to Istanbul’s chief prosecutor, Irfan Fidan. Within seven minutes of walking through the consulate’s front door, Khashoggi was dead. Apparently relying on music to soothe his conscience, the forensic scientist among the assassins then sawed up and possibly destroyed his body. Then they fled the country.

Yet for all the details that have emerged about Khashoggi’s murder, there are still crucial elements of the crime we don’t know—namely, where the body, or what was left of it, was disposed of, and whether Crown Prince Mohammed bin Salman, in whose employ many of the assassins worked, ordered or condoned the killing. How can we find out?

Here’s how: Force the Saudi government to make available Mubarak Mohammed al-Otaibi, the consul-general, who was in his office at the time of the murder. Otaibi was present during Khashoggi’s murder but apparently did not take part. “Do this outside,’’ Otaibi complained to the killers, according to a Turkish official interviewed by the newspaper Yeni Safak. “You’re going to get me in trouble.”

Otaibi left Turkey on October 16th and hasn’t been seen since. The Turkish authorities asked the Saudis to extradite eighteen suspects in connection to the hit squad; the Saudis refused and arrested the men themselves. But what about Otaibi? Of him, the Saudis have been silent. Otaibi is a key: he’s an eyewitness to Khashoggi’s killing. He may have had advance knowledge of the plan, and he might know who ordered it.

M.B.S. and his cohorts in Riyadh seem utterly determined to bury the truth; they have lied repeatedly about Khashoggi’s murder and their government’s involvement in it. The Saudi government’s latest implausible story is that it doesn’t know where Khashoggi’s body is, even though Turkish officials say the killers dispatched a “local collaborator” to get rid of it. Otaibi might be able to shed light on that, too.

Why was the Saudi regime so determined to silence Khashoggi? Perhaps more than any other Saudi, Khashoggi was rooting out the truth about M.B.S.’s draconian ways and sharing it with the world. A few weeks before he was killed, Khashoggi sent me an e-mail urging me to write about M.B.S.’s campaign of arrests. “You will notice the mockery of justice,’’ he wrote. “I’ll be in Istanbul but will take your call.”

In the past year, M.B.S. has embarked on an unprecedented crackdown on domestic dissent, arresting hundreds of journalists, clerics, and women’s-rights activists—anyone who dared to smudge the rosy image of M.B.S. as a benevolent visionary. Not even groups like Human Rights Watch and Amnesty International know for sure how many political prisoners are in Saudi jails. In an interview just after Khashoggi disappeared, M.B.S. told Bloomberg that fifteen hundred Saudis had been arrested in the past three years for such things as “terrorism” and “extremism.” “We are trying to get rid of extremism and terrorism without a civil war,” M.B.S. said.

In one of his final e-mails to me, Khashoggi attached a copy of an indictment in an especially egregious case—that of Salman al-Odah, a cleric in the city of Riyadh. Odah is a well-known and popular critic of the Saudi government who came to notice during the first Gulf War, when he chastised Saudi leaders for inviting American troops into the country. In the nineteen-nineties, he spent several years in prison for allegedly inciting a rebellion against the monarchy. In recent years, Odah has preached a moderate line. Following the 9/11 attacks, he publicly condemned Osama bin Laden for killing innocents and exhorting other Muslims to follow and do likewise. (“My brother Osama,” he said. “Will you be happy to meet God Almighty carrying the burden of these hundreds of thousands or millions of victims on your back?”) In recent years, his criticisms went little further than urging the Saudi monarchy to launch democratic reforms. On Twitter, his Arabic account has fourteen million followers. “My father had a legitimacy independent of the state,” his son, Abdullah Alaoudh, told me. “That’s what the monarchy fears.”

The thirty-seven-count indictment of Odah is basically a series of generalities and accusations without evidence. It accuses him of such things as “cynicism and sarcasm about the government’s achievements,” and “saying that the Saudi leadership monopolizes wealth and is the cause of poverty” in the country. It charges Odah with funding terrorism but offers no facts to back that up.

Indeed, the best anyone can decipher is that Odah’s crime was failing to send out a government-written tweet in support of the Saudi blockade of Qatar, launched with the help of the United Arab Emirates last year. The Saudi and Emirati campaign, apparently aimed at toppling the Qatari government, was—not unlike the indictment of Odah—unsupported by evidence. It was roundly denounced by the United States and much of the rest of the world. “There is not a single allegation against al-Odah of violence or incitement to violence,” Adam Coogle, of Human Rights Watch, said. Even so, prosecutors are seeking the death penalty.

By Saudi standards, the case against Odah is unexceptional. According to Human Rights Watch, in the past year, the Saudi government detained at least thirteen women’s-rights activists and at least sixty clerics. Remember the mass detention, in late 2017, of some two hundred and fifty prominent Saudis, including some of the richest people in the world, in the Ritz-Carlton hotel in Riyadh? The operation, orchestrated by M.B.S. himself, was intended to force the detainees to surrender large parts of their fortunes. Details are sketchy, but it appears that some of the detainees were tortured. At least one man, Ali al-Qahtani, a retired general, died of a heart attack after being subjected to harsh interrogation.

Most of those held inside were released, but more than fifty are still inside. One of them is Prince Turki bin Abdullah, the former governor of Riyadh province. According to a person with ties to Abdullah, the family has been stripped of its wealth and allowed to speak occasionally to Abdullah over the telephone. “We don’t know where he is,” the person told me. There have been persistent rumors that Abdul Aziz bin Fahd—M.B.S.’s cousin and a son of King Fahd—is dead.

It seems increasingly clear that the Trump Administration, which placed M.B.S. at the center of its Middle East strategy, will do nothing to resist the Saudis’ stonewalling of the effort to find the truth about Jamal Khashoggi’s death. Recently, a senior member of the Trump Administration told me that, inside the government, M.B.S. is widely regarded as reckless—but that it was difficult to imagine that Trump would try to push him out. “Trump’s not going to budge,” the official told me.

That puts matters in the hands of the Saudis themselves. While there have been some hints of discontent within the royal family, there so far appears to be no serious consideration of removing M.B.S.—not yet, anyway. In the process of purging the royal court of rivals, the crown prince has made many powerful enemies, some of whom are undoubtedly seething with thoughts of revenge. Even if—especially if—M.B.S. hangs on to his position, it seems likely that the Saudi royal family, and Saudi Arabia more generally, are entering a dangerous period. Bruce Riedel, a Middle East expert at the Brookings Institution, told me, “There is no political way out, except through violence.”