Turkey’s President Recep Tayyip Erdoğan gave a masterclass in creating geopolitical suspense this morning. In the weeks since the disappearance of Jamal Khashoggi, the Saudi journalist, regime critic and Washington Post columnist, newspapers have been full of the medieval horror of his presumed killing. Mr Erdoğan knew his audience had been fed disturbing details of the cold nature of the journalist’s murder and violent dismemberment. He proved a connoisseur of dread, making his audience forget how worldly they thought they were. Instead Mr Erdoğan managed to shock: first by corroborating the story of a mafia-intensity “pre-meditated, brutal murder” in the Saudi consulate in Istanbul by a gang of killers sent from Riyadh. This contradicts Saudi Arabia’s explanation that the writer was accidentally killed. Second was to confirm Mr Erdoğan had no intention of dropping a case that has led Saudi Arabia to its worst diplomatic crisis since 9/11.

The Turkish leader made a point of praising the kingdom’s de jure ruler King Salman but not his son, the de facto monarch Crown Prince Mohammed bin Salman, known as MbS. It seems inconceivable that such an audacious act was carried out without the approval of Prince Mohammed. It is likely that the Turkish government will continue leaking evidence to friendly newspapers that points to such a conclusion. Ever since his father ascended the throne in 2015, the crown prince has ruthlessly consolidated political power and proved an intolerant and vindictive opponent, arresting activists who claimed long-overdue social initiatives were down to their campaigning, not a monarch’s whim. His foreign policy disasters include the bombing and starving of civilians in neighbouring Yemen. The rhetoric of reform and modernisation in Saudi Arabia rings hollow in the face of war crimes and arbitrary jailings.

What Mr Khashoggi’s death did was to instantly escalate Prince Mohammed from wayward, rash royal to a despot like Hafez Assad and Saddam Hussein, who murdered critics abroad and then shook the hands of their bereaved sons at home. Like those other Arab tyrants, MbS finds a brief appearance is apparently so brilliant that no one wants to be the first to stop clapping. Prince Mohammed draws strength from Donald Trump’s administration’s lack of US moral leadership on the world stage. He also knows Mr Trump wants the Saudis close when the next round of US sanctions on Iran take effect in early November. Yet even the US president seems to be waking up to the fact that Riyadh has failed to come up with a defence that holds water, and that pandering to a blatant fiction is costly to a superpower’s reputation.

King Salman ought to take action against those responsible. No one believes this was just the work of MbS’s media adviser and some intelligence officials. The monarch might not have the will or ability to do so – especially if that meant moving against his powerful son. If the international community is satisfied it was murder, it can – and should – impose sanctions and suspend arms sales. The United Nations ought at the very least to censure Riyadh, if not start its own investigation, should Saudi Arabia resist a proper probe. This might protect the Saudi people from their ruthless crown prince – and achieve in death what Mr Khashoggi aimed to do in life.