They had repeatedly been on opposite sides of the Saudi divide. Jamal Khashoggi, the journalist in Riyadh, was the pundit who spoke in favour of the Saudi regime. Yahia Assiri, a 38-year-old former Saudi air force officer living in exile in London, spoke critically. On France 24, BBC, and other channels, they were invited on as talking heads. Mr Assiri said Mr Khashoggi was always polite, and reasonable, not like the Saudi regime defender who just last month angrily called for his execution in a segment that was edited out.

Then one day late last year, Mr Khashoggi popped up in London and asked to see Mr Assiri. Over tea in the lobby of an upmarket West End hotel, Mr Khashoggi made an astonishing admission: he told Mr Assiri he had been right about the Saudi regime, and that Khashoggi himself now sought to join the opposition.

“He said, ‘I am exactly like you’,” Mr Assiri recalled. “‘I want democracy and freedom. I wanted it to be done more smoothly. I wanted to do it from the inside. But it’s not possible’.”

I’ve heard people very comfortably complain about what’s going on with the government. It’s just that now, it’s not tolerated in Saudi Arabia. That’s what’s evolved and changed Sarah Leah Whitson, Middle East director at HRW

Mr Khashoggi’s fate remains a mystery a week after he was caught on CCTV walking into the Saudi consulate in Istanbul but then, according to Turkish officials, failed to leave. Friends and family members remain full of dread after Turkish officials said their preliminary conclusion – based on security camera footage and airport transit data – suggested that the 59-year-old had been killed inside the consulate, possibly dismembered, and removed from the facility with the help of 15 mysterious men somehow connected to Saudi authorities.

Mr Assiri and others who knew Mr Khashoggi say his trajectory from loyal supporter of the Saudi system with strong ties to the elite to thoughtful dissident abroad made him a prime target for the Saudi security forces under the leadership of the country’s ambitious and powerful Crown Prince Mohammad bin Salman.

His transformation was rooted in both his own intellectual evolution as well as the increasingly intolerant Saudi state that made it all but impossible for even mild critics to have a voice.

“His views are the views that many Saudis I know have always expressed,” said Sarah Leah Whitson, Middle East director of Human Rights Watch, and a friend of Mr Khashoggi.

“I’ve heard people very comfortably complain about what’s going on with the government. It’s just that now, it’s not tolerated in Saudi Arabia. That’s what’s evolved and changed.”

Mr Khashoggi had parallel careers. He was both a journalist and an adviser to a powerful Saudi prince, Turki bin Faisal, who has served as chief of intelligence, as well as ambassador to the US and UK. He later explained to friends that as Prince Turki’s right-hand man, he was obliged to serve as a mouthpiece of the Saudi regime. But he also had access to the inner workings of secret Saudi dealings, including activities abroad such as newspapers, television outlets, pundits discreetly bankrolled by Riyadh and sycophantic royals seeking the favour of the monarchical elite.

Protesters in Istanbul demand answers in the disappearance of Saudi journalist Jamal Khasoggi.

As a journalist, however, Mr Khashoggi had long harboured doubts about Saudi Arabia’s course. “Even when he was supporting the government, he was always saying we all want to have freedom and want our demands met,” recalled Mr Assiri. “He would say, ‘Our government will do it in the future. Be optimistic.’”

Even before his self-imposed exile, friction began to mount, beginning under King Abdullah, predecessor to the reigning King Salman. He was fired from the editorship of al-Watan, a leading Saudi newspaper. In 2015, Mr Khashoggi was named head of the new Bahrain-based pan-Arab television channel bankrolled by Prince al-Waleed bin Talal; it was ordered to close down within hours of its launch.

The final straw came with the arrests of hundreds of royal family members, including Bin Talal, on vague corruption charges. They were locked up inside the Ritz Carlton hotel in Riyadh, with some allegedly subjected to torture.

“He was very conflicted about what to do,” recalled Human Rights Watch’s Ms Whitson. “It was very much, ‘Do I stay, or do I go?’ They had already fired him from numerous positions. They had banned him from writing. He concluded very rightly that he wasn’t safe any more.”

He was warmly embraced by the US where he found numerous audiences for his work, as well as an exchange of ideas with scholars, journalists, activists, and policymakers outside of his normal sphere. In Washington, he was also able to spread his views uncensored, and in The Washington Post opinion pages, he acquired a platform to get his ideas out to a wide audience. He was highly in demand by think tanks – at least those that weren’t funded by the Saudis.

“He came much more frequently in contact with a much wider array of people who had nuanced understandings of what was happening in Saudi Arabia and the region,” said Ms Whitson.

Jamal Khashoggi on Al Jazeera earlier this year – the channel is owned by Saudi Arabia’s rival Qatar

Over the past year, observers detected a sharpening of Mr Khashoggi’s criticism against of the Saudi leadership, and growing confidence about his opposition to the Crown Prince’s reign. In March, he told Al Jazeera, hosted and funded by the Saudi leadership’s nemesis, Qatar, that Saudi Arabia would never evolve into a democracy under the current leadership.

“I haven’t heard [Crown Prince Salman] make even the slightest inference that he would open the country for power-sharing, for democracy,” he said.

Since his departure from Saudi Arabia, friends say he even began to account for his dual role, as a journalist and as an adjutant to the powerful Prince Bin Turki. At the meeting in the hotel lobby, Mr Assiri pressed him about his ties to the Saudi security and intelligence apparatus. “He gave me concrete answers that gave me trust and confidence,” he said, declining to reveal specific details of the private conversation.

Joseph Bahout, a French-Lebanese scholar and friend of Mr Khashoggi, said that while he had long been a mild critic of the Saudi system, his views were changing, even hardening. In recent months, he had begun to express opposition to the Saudi war in Yemen, which is being waged by Crown Prince bin Salman. He had begun to liken the Crown Prince to Russia president Vladimir Putin and Iran’s supreme leader, Ali Khamenei.

“He evolved gradually over the last two or three years; this is an evolution we all have,” he said. “It was prompted by the behaviours and excesses of the Crown Prince.”

Saudi Arabia’s ambassador to the US, Prince Khalid bin Salman, said that Mr Khashoggi continued to maintain ties with Saudi officials even after he left his country.

More than anything, I think he was personally scared of Mohammed bin Salman Selim Sazak, academic

“Jamal has many friends in the Kingdom, including myself, and despite our differences, and his choice to go into his so called ‘self-exile’, we still maintained regular contact when he was in Washington,” he said in a statement, denying his government had anything to do with his disappearance.

During his time in Washington, he was an increasing presence at talks, lectures, and soirees where scholars, diplomats, and journalists mingle. Selim Sazak, a Turkish scholar based in Washington, ran into Mr Khashoggi perhaps half a dozen times over the past year. He described him as sharp, quick-witted and a bit of a “contrarian”, always on the lookout for a good debate. He did not appear to be guided by any particular ideology – not Islamism or secularism or liberalism. He was mostly focused on the Crown Prince.