The Saudi Arabian journalist Jamal Khashoggi was well known for much of his adult life – certainly to anyone following the notoriously opaque politics of his native country. But the terrible circumstances of his death brought him instant fame that focused global attention on the conservative kingdom.

Khashoggi was 59 when he was killed after entering the Saudi consulate in Istanbul on 2 October. Official denials, leaks and feverish speculation about his fate fuelled tensions between the Turkish and Saudi governments, long at odds. Revelation of the chilling details exposed the brutality of a supposedly modernising monarchy in Riyadh in crushing dissent.

The final chapter of Khashoggi’s life began just over a year before his death, when he left his home in Jeddah for self-imposed exile in the US. He attracted attention by writing columns for the Washington Post, focusing on the changes that had taken place since the ageing King Salman had appointed his youngest son, Mohammed, as crown prince in June 2017.

Khashoggi watched as Mohammed bin Salman sought to wean Saudi Arabia off its long dependence on oil and drove through unprecedented social changes that included lifting the ban on women driving. But his high-profile campaign against corruption meant locking up princes and businessmen in a luxury hotel and arbitrarily jailing or silencing critics, whether liberals or Islamists seeking political reform or conservatives alarmed by his approach.

Khashoggi’s views on the young prince added to Bin Salman’s reputation for recklessness as he pursued an ill-conceived war in support of the government of Yemen as well as launching a bitterly divisive boycott of neighbouring Qatar. Hostility to Iran and its regional allies was central to his strategy.

The columnist described himself as frustrated that he no longer had a Saudi outlet – though his Post articles were also published in Arabic and his 1.6m Twitter followers ensured a vast audience. He called Bin Salman a “brash and abrasive young innovator” and compared him to Vladimir Putin. However, he always insisted that he did not see himself as a dissident, but as a Saudi patriot.

Indeed, he had once been close to the Al Saud dynasty, whose patronage was necessary for even an independent-minded journalist. He always said that the kingdom should not be treated as a special case. He told friends that moving abroad had been the hardest decision of his life. “With each new critical article, the gap between him and the decision-makers in Riyadh widened,” commented a Gulf colleague who agreed with some of Khashoggi’s views but feared he had gone too far in criticising the royal family.

Born in Medina, Jamal came from a well-known family of Turkish origin that had migrated to the western Hijaz region of the Arabian peninsula in Ottoman times. He was the son of Ahmad Khashoggi, the owner of a fabric shop, and his wife Esaaf (nee Daftar). The arms dealer Adnan Khashoggi was a relative. “Jamal used to talk about missing Eid in Medina,” an American friend recalled. “He had vivid memories of growing up there. He longed to be home, like any exile.”

Jamal went to school in Saudi Arabia before leaving for the US where, in 1982, he gained a BA in business administration at Indiana State University – providing the basis for the fluent English that enhanced his professional profile. His journalistic life proper began in 1986 on the English-language Arab News and the Arabic newspaper Okaz. He also wrote for the influential London-based Arabic dailies Al-Sharq al-Awsat and Al-Hayat.

He covered the Soviet war in Afghanistan and the rise of Osama bin Laden, whom he had known earlier, interviewing him both there and in Sudan. Like many of his countrymen, Khashoggi sympathised with the Saudi and CIA-backed mujahideen fighting the Red Army forces. Otherwise his own views were moderately Islamist – of the Muslim Brotherhood school. That was part of his ambivalent status within Saudi society and vis-a-vis the regime: he was too Islamist for secular-minded liberals but too liberal for traditional conservative Wahhabis.

In 1999-2000, he was the managing editor of Arab News and then editor of the Riyadh-based Al-Watan daily, but he was sacked after criticising the religious establishment. Still, his royal connections allowed him to serve as media adviser (2003-07) to Prince Turki al Faisal, the veteran head of the Saudi general intelligence service and, at that time, the kingdom’s ambassador to London and then to Washington. In 2007, Khashoggi was reinstated as editor of Al-Watan, but he resigned in 2010 after a row over running another controversial opinion piece.

Under King Abdullah, he believed it might be possible to combine social and economic modernisation with the gradual relaxation of freedom of expression. In 2015, when Bin Salman ascended the throne, Khashoggi was appointed to run the Bahrain-based Al-Arab TV station, owned by the billionaire Prince Alwaleed bin Talal, to compete with the influential Qatari-run Al-Jazeera. But the new channel was shut down after its inaugural broadcast.

Khashoggi came to the conclusion that Bin Salman was more rogue than reformer and could not succeed in delivering both modernity and freedom. Supporters of the crown prince accused Khashoggi of trying to revive an Islamist current that had been initially empowered during the Arab spring but defeated by the counter-revolutions in Egypt and the Gulf. Loyalist media called him traitor or an apostate, or implied that he was working for the Qataris.

Writing from afar, he helped US and western journalists, policy-makers and politicians understand what was happening in the kingdom. In March 2018, he wrote in the Guardian that Bin Salman “appears to be moving the country from old-time religious extremism to his own ‘You-must-accept-my-reform’ extremism, without any consultation – accompanied by arrests and the disappearance of his critics.” His last Washington Post column lambasted the “cruel” Saudi role in the war in Yemen. Days before his murder, he was a guest speaker at an international conference on Palestine in London. Khashoggi’s admirers described him as a shahid (martyr).

He is survived by his fiancee, Hatice Cengiz, and the two sons and two daughters from his first marriage, to Rawia al-Tunisi. It ended in divorce, as did two other marriages.

• Jamal Ahmad Khashoggi, journalist, born 13 October 1958; died 2 October 2018

• This article was amended on 21 October 2018. The original stated that Jamal Khashoggi began his journalistic life at Saudi Gazette. It was in fact at Arab News.